Personally, I don't worry about spamming crafts (not usually encrusted mugs, but loads and loads of mugs, rings, earrings, etc) and raising my invasion-potential, because of my lock-in design, and I get more immigrants! (Assuming they survive the trip inside, but there's a good chance that they will as that's also part of my planning.)
When you've got loads of immigrants, certainly, and often from about two seasons in, I'll have someone who isn't actually too skilled with a desired civvie skill but either has a definite military skill or can be drafted anyway, without too much worry about civvie skills (save for whatever I decide to give them to keep their off-time happy and productive). Putting such dwarves in training squads (keeping any family-attached ones in a reserve-as-last-ditch squad, so that the unattached ones can be safely used without risk of sparking a grief-then-tantrum cycle), I find I often get a decent small-squad military. Sufficient for my purposes. And crossbows are my forte.
I've more or less perfected (to my satisfaction) a firing range design that means minimum ammo loss (each range is a finger of floor surrounded by channels to each side and behind the target, with walls beyond, so anything but a direct hit on target from the maximum distance hits the walls and falls below to a handy bolt-stockpile) and once anyone training with them has attained enough skill to be destroying their training bolts on the target I can remove them from the range-training squad, and perhaps add them (back to?) the wrestling or even crossbow-hammering squad. But as I also tend to build overlooks, to deal with any awkward enemies (and give them enough armour to get a good chance against enemy snipers firing back through the fortifications involved), the melee troops rarely get active battlefield practice and the crossbow dwarves only ever get sent into physical contact with a hostile when they're basically doomed. (Or, in one case, because I'd chipped an amber FB as much as I could possibly do, broken most of its body bits with metal bolts and was bored, so I opened the right lever-controlled drawbridges to get the crossbowdwarf squad in contact and one of them got the final hit that actually killed it.)
But, I do loads of other things, like that whole "isolate behind drawbridges and ditches" thing, that means that this is possible and probably my biggest defensive unit is the current cohort of construction-fulfilling masons, and the occasional mechanic and trap-loader... If I have to use the military, it's generally because I'm fed up with the stalemate of the trapped enemy (who aren't going anywhere, in or out, and that I can easily bypass by opening a separate route).