My current default design involves digging a 3-wide hallway, and a 3x3 central stairway for the whole fort. Five zlevels lower I dig out the "workfloor" - the general purpose stockpile, workshops and their stockpiles, ad anything related to industry. One zlevel under that I dig out the "civ floor" - the dining room, the kitchen, the nobles' rooms, and later bedroom for every dwarf. After reaching self-sustainingness, I start various projects including the graveyard, water reservoir and well, appartments, and much later, when making coke starts to annoy me, a magma-powered metal industry.
Describing my design strategy in a script would be like this:
Embark site requires some or little soil, shallow metals(some form of iron especially), deep metals and flux. Needs a suitable hill, the side of which must be at least 30 tiles away from the surface. Aquifers are to be avoided but tolerated. Any temperature, but trees must be "Woodland" or more. Plenty of other vegetation is preferred. Alignment must be "calm", "wilderness", or "mirthful". If I'm feeling lucky "untamed wilds", "Serene", or "Sinster". River should be avoided but is tolerated. Area must cover 3x3 that meets all these requirements.
1. Start by designating 5 trees to be chopped and digging out one-wide hallway, 20 tiles long, followed by central stairwell for entire fort. If no suitable hills to dig into are present, abandon and search for another site. Also designate 10x10 refuse stockpile, preferably far from the enterance.
2. 5 zlevels below surface, dig out general purpose stockpile with everything except refuse, corpses, wood, and stone. Next to that dig out workshop area with a carpenter's, mason's, and mechanic's, along with a stone and wood stockpile. 1x1 garbage dump, too.
3. Under that, dig out a 10 tile wide hallway with a 10x10 dining hall at the end. In the meantime, order 5 wooden tables, 5 rock thrones, and a rock door to be made. These will be placed in the dining hall later later.
4. Dig out kitchen area. Room should be 10x10 large. Room has a kitchen(workshop), still, and a fishery. A 3x3 room behind a door has the butcher's shop. The remaining space is filled with a stockpile that accepts everything in the food category, except for seeds, and also allows barrels and pots.
5. Dig out room for the metal industry. Unless we haven't had migrants yet, put a forge and 3 smelters. Start digging out metal ores and coal. If no coal is present, build a wood furnace and set make charcoal to work fulltime. Assign a bookkeeper and manager which both are the same dwarf, preferably some unskilled farmer or such. Remove all of his labors. Bookkeeping precision will start at low and will be increased every time I see inaccurate numbers. Order 30 barrels and once ten are made, set making booze on repeat.
6. Order 5 beds to be made and dig out a dormitory.
7. Start making 30 bins, routinely every 2 seasons until the 3rd year.
8. Stuff the hallway with three rows of stone falls, 4 cage traps, and 5 weapon traps in that order. Weapon traps are equipped with 3 iron discs, 3 iron spikes, and 3 iron spiked balls each.
9. Select ten unused dwarves and draft them into the militia. Order 10 iron axes, and 10 iron breastplates, leggings, and helmets, to be made, and ten wooden shields. Make a barracks just outside the front gate. After the 4th migrant wave, start making steel and replace all iron armor and weapons with steel versions. Melt all iron equipment. From that point, draft more migrants until we have an axe squad, a sword squad, a crossbow squad, and a mace squad, with 10 soldiers each. Prepare burrows and alert levels. Training rotation is at least 6 dwarves at all times all year.
9. By now we're self-sustaining. Many projects will follow. The first one will be a water reservoir filled with water from the caverns. (If there's no water, then, well shit) The windmill battery to power the pump stack will be reused in the future for other powered stuff. The second project is building every type of workshop, largely useless but always useful to have ready.
10. The third major project is a large outer wall around the enterance, with plenty of inner space, a roof, and fortifications. Draft many unoccupied dwarves with the carpenter labor regardless if they have skill. Don't bother disabling after the wall is done.
11. The fourth major project is appartments. A 3x3 room for every dwarf, with a cabinet in each room. Smoothe and engrave the whole thing afterwards.
12. After a while, making coke will become annoying. Dig down to magma. Try to avoid the caverns and do not explore them. To save FPS.
13. After reaching the 150 population milestone, and with at least 2 legendary melee squads, dig candy. Start by replacing the weapons with candy ones, except for the maces.
14. From this point, the fort will be subject to boredom and !!SCIENCE!!. After lots of boredom, retire and visit in adventure mode.