I've never had much trouble with organizing. First 7 do everything till I get a couple migrant waves. Then I start putting anyone with military skill (and often some without) into training squads. And like someone else said, start having people dump lots of copper into bolts for strange moods. Only have 1 weapon/armorsmith of any skill, unless i get a mooded legendary one.
A newer fort that I've been playing though, I've been doing as a "human town" style. Theres still an underground but currently all 30 of my dorfs live above ground in 3 story wooden houses (forest biome). All the houses are sized such that they could fit maybe 6 dorfs comfordably. Mainly, the houses that there are, each house a pair of crafters or w/e, in most cases they're married. The ground floor has 2 workshops. And the basement is storage usually relating to their job. Then in the center of town theres a large communal feasting hall, food storage basement, and the second floor is a large dorm for new migrants who haven't found a place in the world yet.
Dedicated haulers still live in houses with their spouses, however their workshop is removed and theres just more storage space.
Really this fort kinda sucks because of all the micromanaging. But I'm up to 58 dorfs (7 children, not counting them) so far. 22 Skilled people; 2 Cooks, 2 Brewers, 2 Threshers/clothesmaker/spinner/milker (all 6 of them also cover farming needs) 2 miners, 4 cutters, 1 glasser, 1 weaponsmith, 1 armorsmith, 1 beekeeper (figured why not. His roof is covered in hives) 2 dedicated woodburners. 1 Bookkeeper/manager/trader, 1 Carpenter/stonemason
and 2 "crafters" primarily wood. Also misc other tasks are mixed in with the above. 1 of the cooks has buchering, 1 of the brewers covers tanning, and things like that. Then I've got 6 fulltime haulers, who also have carpentry checked but can't work at the carpenters shop (this is so they can place all the wooden walls and such that I need) The other 30 are militia/haulers. 20 of them are crossbows,(4 squads) and 10 are melees (2 squads of 5, each squad is 1 sword, 1 axe, 1 spear, 1 hammer, and 1 pick).
Really this fort sucks, so much extra work. And when someone dies, I can't wait to see how intense the tantrum spiral gets, because currently all but 10 of the dorfs are married, and the kids are all from different families, but if I keep playing like this, they'll all end up intermarried, and more migrants, and it'll get CRAZY. But thats all part of the fun.