I've run my share of fortresses into the ground (some pun intended), and I've come up with a few "plans" I try to follow.
I am very picky about my embark. I play with worldgen parameters a bit - increase the "min number of volcano's to about 160 for a large region. I lower the mineral scarcity to about 150. This often means a lot of reject worlds, if it complains I'll reduce the volcanoes or increase the scarcity a bit. I also have the Masterwork Mod, so I have aquifiers disabled. I look for Deep Soil, Shallow Minerals, and Flux. I also want a warm or hot climate, (temperate or colder means the water will freeze in the winter, and hot or scorching seem to have problems with fires) and lots of trees (ie, woodland or heavily forested). I prefer sand, but will settle for clay. I also want a volcano and a brook/river both in a 4x4 embark.
Deep soil means easy digging at first. I can quickly dig out space for stockpiles without the clutter of digging in rock - and you can grow stuff in an underground soil layer without creating mud first, so food/booze production is easier. It also is quick to dig and levels up miners quickly.
I want sand or clay to make pots - you can't afford to go through all your wood making barrels. Sand tends to be better, because clay pots need to be glazed to hold liquids (except fire clay, which doesn't need glazing). Glass can also be used to make screw pump parts (non magma-safe) and spikes/discs for weapon traps (almost as good as steel).
I want the volcano so I can get magma powered kilns, smelters, forges, early on. This lets me reserve fuel for making steel (which needs fuel even with magma - it provides the carbon) I want the running water (and a climate where it won't freeze) both to provide plenty of water for drinking (especially for the well in the hospital), the "fountain" just outside the dining hall (so my dorfs get happy mist thoughts every time they eat), and power year 'round.
I also use the "prepare carefully" option. I sell an axe (one woodcutter is enough) and buy another pick (for a total of three). I sell off buckets, wheelbarows, etc (stuff I can easily make) so I can buy livestock. I bring breeding pairs of; dogs, cats, chickens, turkeys, and sheep. You get two horses free - so I hope for a breeding pair. More often than not, I get two of the same sex, so I trade for the missing gender as soon as I can.
I look over my dorfs, and give the most suitable one (the one I want for leader) one skill level of Appraisal, Negotiating, Recordkeeping, and Architecture. The last is because dorfs with no skill in architecture really don't like to take jobs designing buildings - even with the task enabled they will sit around for weeks with "No Job" rather than design that drawbridge or smelter, etc. I pick my laziest, weakest dorf to be my medic, giving him one skill in each of the medical jobs.
I designate a "water" zone, just in case I run out of booze (dorfs often won't drink water unless a sone is designated - and will die of dehydration right next to drinkable water!)
I have an old computer, and only get about 10-15 fps after a couple seasons, so I cheat a bit to ensure I'm not wasting a week or two of playtime on an embark that doesn't have all the required resources. I'll use dfhack to "prospect all", and even changelayer and changevein to ensure at least the minimum resources are available (enough to get me to where I can trade for what I don't have).
After I've saved the "improved" embark and backed it up, I'll unpause.
My three dorfs with the highest stamina get assigned to mining. I don't worry about strenght - mining builds that quickly. Fourth highest gets Treecutting. My expedition leader gets Plant Gathering, Architecture, Mechanics, Carpentry, Woodcrafting, Stonecrafting, and Fish cleaning right away. The medical dorf gets plant gathering, and the "leftover" gets plant gathering and brewing assigned. Everyone hauls everything at the start.
I like to have a large flat area - usually at "ground level" (determined by the river/brook). This provides space for gardening, pastures, and early workshops. I try to find a good place for an entrance near the center of the map, but still at "ground level". I designate the trees near that entrance to be cut, and designate a decent sized area for plant gathering. I designate the digging for the entrance - digging into a slope, and channelling a dry moat in front of the entrance (leaving ramps for now). The channeling is done now just so I don't forget to plan around it later.
I dig a bit into the hillside, but quickly go down a level. This usually done with a 4x4 stairway stairway, but may be ramps, depending on the terrain. I want access to a soil layer - so I can dig out space for stockpiles. First I dig out an area (two levels below "ground level" for food stockpiles. I make two - one for food, and one for booze. I make sure that the food pile doesn't accept raw fish or eggs. I make a separate food pile for ray fish outside, and build a Fishery next to it. Once my leader has built the fishery (out of wood - I usually don't have stone yet), I give the medical dorf fishing and fish cleaning. This provides food and also provides shells - and sooner or later some moody dorf will want shells.
I also build a refuse pile somewhere near the entrance, but outside (of course).
I also build a Carpenters shop early (and give the woodcutter carpentry, and remove carpentry from the leader), a craftdwarfs shop, and a still. Then I'll build a masons shop and a mechanics shop (all out of wood). I make a few nest boxes (from stone), and build them, so my chickens and turkeys can reproduce (once I get enough chicks and poults, I enable the food stockpile for the appropriate eggs).
After my miners have dug out the food stockpiles, I have then dig a good sized wood stockpile one z below "ground level", and build a new carpenters shop (hopefully by now I have a couple rocks to build with). By this time I usually have a fair amount of wood cut, so I can have the woodcutter/carpenter make some buckets, wheelbarrows and barrels.
I'll also dig out room for a "generic" stockpile - one that accepts everything but food, refuse, wood, and stone. By the end of summer I want everything off the wagon and stored inside. I create a "pen/pasture" zone in the entrance and put all the dogs there (to prevent thieves) and have someone train them as wardogs. You don't want a thief top get away with loot because you will get an invasion soon after. I pasture the birds around the nest boxes, and create a large zone to pasture the sheep, horses, whatever. While grazing is broken, this still prevents the livestock from crowding the meeting hall.
With the Masterwork Mod, I also build a Loom right away (and give the farmer dorf weaving) because Masterwork has surface plants that can generate webs - so I get silk right away. I also build a Tannery and Leatherworker's shop because many fish provide "chitinplate" which can be used to make bags (always in short supply early on).
By midsummer, I will have dug out around the stockpiles so I can put a still and a kitchen next to the food pile, a carpenter next to the wood pile, and a mason's shop, mechanics shop, and craft shop next to the "generic" pile. I'll destroy the outside shops (ecxept the draft shop, which I leave so I have two (because sooner or later, one will be taken over by a moody dorf). I'll put two smaller stockpiles next to the food and booze piles - one just for barrels/large pots, and the other just for bags (and remember to disable those from the "generic" pile. Also, I want a Trade Depot (outside still) by the end of summer.
After that, I'll dig out space for a couple gem piles (one raw, one cut) and a jewelers shop. The first year or so, cut gems are usually my best trade good. Then I dig out space for a dining room and dormitory near the entrance (often at "ground level). Also, I dog out and furnish a 5x5 office and dining room assigned to the leader. Then he gets assigned as the broker and bookkeeper (at second to lowest precision, so I know what I actually have to work with - precision gets raised up over time). Then I dig out space for 3 or four stone piles near the masonry and mechanics shop (used to use just one pile, but wheelbarrows changed that)
By this time, I will have turned off hauling for my miners, and I'll start the magma tap. These days, the only safe way to tap a vent is from the top, so I'll have a 4-wide channel for the magma - building walls if needed because the top of the magma vent is above the surrounding terrain. Once I get a couple levels down, I'll widen out the channel to 6 wide and carve some fortifications. Then I'll start from the bottom up - one or two levels below the lowest soil level, and I'll dig ramps up to the fortification (the fortification prevents lava sprites, etc, from getting into my fort). At the bottom of the chute, I dig a three-wide tunnel to the nearest edge of the map, and carve fortifications into the edge (this allow fluids to drain "off the map"). I'll close off the top with floodgates or floorhatches, and build a raising drawbridge to close the drain tunnel. All will be connected to one lever, so I works as a "Drain - Fill" switch. Note that I still haven't channeled out the edge of the lava tube yet - that won't get done until all the loose rocks are removed and the gates all connected. Once that's dug out (but before it's cleaned and connected) at the bottom of the chute, I dig a four-wide tunnel to the area where I'll be setting up my magma industries. I put raising bridges at the entrance to the "lava grid", and at the drain for the grid. These get connected to separate levers. This allows me to drain the main magma supply (so I can tap the supply to power traps later) without draining the forge supply "grid". When I dig the chute and grid, I dig out any gems or ores adjacent, and build walls to replace them (so I can come back and dig out the rest of the vein later. After the grid is dug out it's usually autumn, so I start digging a dry moat. I keep it at least two tiles from the edge (so immigrants, invasions, and traders don't get stuck in "limbo", and remove upward slopes, etc, so that there is only one way into my area. Then a new "pen" is designated, and the dogs moved to watch that new entrance. Eventually, walls will be built just inside that moat to protect against archers - and I also use channels and "remove upward ramps" to isolate the area at least 5 levels above "ground level". A one-wide tunnel will be dug to allow access to the areas outside my enclosure, and heavily trapped (and protected with at least one dog). A new Trade Depot will be built, with access to only one spot on one edge of the Map - this ensures that traders will arrive in that one spot and makes them easier to protect. It is also "airlocked", the depot is either accessible to the fort, or to the ouside, but never both.
You may have noticed that I still haven't built individual bedrooms yet, or spent much effort on the dining hall. I have just enough beds so no one sleeps on the floor. I want my dorfs a bit annoyed - because I want strange moods. They are a pain to deal with - but it's a good way to get legendary skills. I make sure that I have some of everything - so it's rare that a dorf goes nuts. The artifacts can be used to improve room values later on when I get slackers - er, I mean nobles.
By the time the moat is dug, the magma grid is almost cleaned out, so I dig out spaces for the smelters, forges, kilns, etc. Smelters will be at one edge of the grid, and ore piles on the same level and one level up. One level above the smelters/forges I'll have bar/block piles, and one level above that I'll create piles for the goods produced. Long rows of staircases(spaced every 6 tiles) connect the levels. As I add these piles, I change the "generic" pile to exclude them - it becomes my main furniture/mechanism pile.
I don't use hunting, it's just a good way to lose dorfs and ammo. I rely on fishing at first, then add in eggs (have to be boiled before they are edible) to provide most of the food - gathered plants are brewed as soon as possible to prevent them from being eaten. I also start outdoor farming the first summer, but don't have many seeds so it takes a couple years for farming to get up to speed. Indoor farming is also started as soon as I can - for the same reason. I won't need the food at first, but it allows me to increase my seed supply.
Main focuses for the first couple years are Booze and Food production (including barrels and bags), and getting the magma factories ready. I start by making a half dozen buckets (so dorfs can "give water" and milk animals), then a dozen or so barrels. Then I make a half dozen beds, then alternate barrels and bins. I use stone for chairs, tables, mechanisms, floodgates, etc.
Once the magma is ready, I stop making wood barrels and start making large pots from glass or clay. I make bins from whatever "utility" metal I have a lot of, often copper. Wood then gets saved for beds, lye, and fertilizer.
I try to keep 75 - 125 drinks until the second wave of immigrants hits, then I up that to 150 - 200. I keep about 4 dorfs with fish cleaning for every fisher - and fishers have fish cleaning as well. Between fish and turkey eggs, food isn't usually a problem. I build a fountain (self powered pumpstack three levels high to provide a waterfall) right outside the dining hall, and smooth/engrave the walls of the hall. Later, I'll do bedrooms the same way, and have ecstatic dorfs everywhere. As soon as kids start showing up, I'll make sure I have cloths available. Losing a kid to insanity and death seems to really upset dorfs - try to avoid it.
If I think of it, I'll take some screenies of my current fort, so I can demonstrate the layout. Efficiency matters, and you really have to think three dimensionally to keep distances short and keep a good production rate while avoiding cluttering shops.
It isn't a problem on my antique computer, but on a newer machine you may want to limit the FPS to around 75. At the default (150) it can be hard to stay on top of things and you'll have dorfs idle a lot. You can't really waste dorf-hours that way, especially at the beginning, or you won't be ready for immigrants - the first thing they do is drink and eat, and want a place to sleep.
General advice:
Don't be stingy with stairs. If dorfs have to walk far to stairs to get something right above (or below) them it can really slow down production. Dorfs can walk through a staircase like it is level ground, so the only drawback to stairs is that they block building and can interfere with stockpiles.
Try to have the moat dug by the first fall - that's when the first thief will appear. If he get's away with any goods, an invasion will follow in a couple seasons.
Don't sell anything made of wood to Elves - including things in wooden barrels or bins. They will get angry and invade sooner or later.
Watch the cat population. While you need some cats to kill vermin, they reproduce faster than rabbits. I maintain two males and six females - and butcher a lot of kittens as soon as they are born (before they adopt someone). You won't get bone or hide from kittens, but you will usually get a small amount of meat, and some fat (for soap).
Dogs are your best defense for the first year or two - use Pen/Pasture zones to place them at entrances. Train them as soon as you can spare the time.
For dorfs that will be going outside the compound, like plant gatherers and woodcutters/wood haulers, have them train a wardog, then don't assign that dog to anyone or pen it. A dog will follow the person who trained it until you assign it - so this gives the woodcutter (or whatever) the benefit of having a wardog's protection, but since it hasn't been assigned to him it isn't a pet and he won't get sad if the wardog get's killed - just have him train another.
Most of all, think traffic flow - in three dimensions. Halls should be at least 3-wide, and stairs 3x3 (4x4 is better).
Keep an eye on new animals - the latest version will automatically assign a new-born animal to the same pen as it's mother - but older versions don't (this is important if you use Masterwork, which is a version behind). Unpastured animals get in the way, and can quickly crowd your dining hall.
Make sure that at least one breeding pair of every type of animal is available as a pet. This will help prevent accidentally butchering your last male, etc. Some tilesets (yes, I'm talking about you, Phobius) display an asterisk for both genders, rather than the distinct gender signs - so you won't be able to determine the gender of many animals from the screen where you select the ones to butcher.
Fish. It provides a lot of food, and also provides shells. Shell crafts aren't worth much, but it seems to be a VERY popular item with moody dorfs, so it's good to have a ready supply.
Try to keep a small stock of EVERYTHING. It sucks to have to butcher your only bull because some moody dorf wants to carve some bones. Or worse, have them go ballistic because you don't have that silk cloth and uncut gems they think they need - to make a storage bin.
