I have been playing with a completly open fort and this is how i have managed.
1st grab the 2 strongest/agilist start ghouls as your start military (or even better vampires if you get any in the migration waves)
Start with a pair or copper (or better) scourges and shields
At the start of the embark make a Uniform with no item, replacing clothing and assign it to all everyone.
Now equip your two ghouls using specific item, you should be able to equip them with a complete set of metal grade (chitin/scale) covereing (shoes/trousers/shirt/gloves/robes/cloak), and a metal mask (a start dreadnaught mask is ideal)
Remove everyone else from the military to pick up the remaining clothing.
If you dont have complete coverage repeat after a migration wave, note that arriving skeletons drop clothing in a {forbidden} pile on the map square they arrive on so will need to go and re-claim it.
Your ghouls should now be safe to slaughter the wildlife (watch out for giant animals/saquatches that may still rip off their heads with wrestling moves)
Next aim if to collect a bunch of souls (with constant attacks on wildlife) to boost agility and strength, and enough chitin/scale to make sets of leather armour to add on top of the leather clothing. Note if you boost agility to 3000+ first will massive speed up soul collection as can easily catch wildlife, rather than chase->chase->chase->hit once->chase->chase->chase etc)
Boosted to 5000 strength/agility even bronze scouges will penetrate steel armor.
In my case i lost my start 2 ghouls reasonably early to giant animals, but luckly replaced them with vampires.
If you can defeat the first ambush should give you both steel armor, larger shields and enough steel items to start armouring up your warrior pair. If needed temporary stick all the skelletons in a squad & attack the ambush as a distraction for the ghouls doing the killing. Just make you have a couple of {stored souls} stashed to resurect them. Upgrading to ironbone does not make them much better in a fight but does seem to make them harder to finish off, so them make a better distraction. (dfhack 'killitwith gravity' may be your friend to dispose of injured skeletons so they can be re-raised)
Work on a fully layered armor set likly of ironbone early and replace with steel/bloodsteel/mithril (full set of chinin/scale clothing, cloak, robe + full steel mail + full steel plate) for your two warrirors as they have the strength to wear it without slowing down. Early on can use ethereal forge to make equipment, but use a skelleton so that if a masterwork item is created and then destroys itself dont send a warlock insane.
My two vamps (year 5) are presently taking out entire sieges by themselves, with only the occasional broken bone (which heals in a month or two, and with 5000 willpower not stuck in bed while healing)
If you are using vamps look out for pikes/halaberds as this is the only weapon they can gain exp in (occasioanlly brought by humans, can get for relics/treasue in the arceologist). Im presently using pair of Ledgendary Pike, even if they are made of rusty steel & iron.
Just starting to learn spells and are focusing on defenseive ones (e.g. Armor), vampires already take 50% damage, stacking additional reduced damage modifies makes them almost invunerable.
Everyone except the skelletons are wearing a full set of mithril armor (from melted elven gear) and are restricted to inside the tower/dungeons and the two vampires (who are never off duty as dont need to sleep/eat) train just outside the tower entrance. Minimizes friendly casulties, and if a buch of skelletons are caught outside in an attack they are cheap to re-raise.