Goblins also tend to be rather weak, especially individually. I send groups of 3-5 untrained, unarmed, unarmored migrants in to go kill the dudes, and they either get caught and die, or end up with skull-in-the-brain syndromes.
I would disagree about untrained ones. A group of 10 bow goblins will seriously make a mess of untrained unarmored (and most likely armored ones also) dwarves.
Personally i just train 2 ultra godly ones and kill massive sieges with it
A simple way to ensure you're good to go early on. Is of your starting 7, put 2 of them as military of the same type (hammer/sword i generally find the best). so proficient in weapon skill, (i also add +5 dodger to one and +5 striker to the other, as they level slowly without some points thrown in). At embark add copper weapons, if you can afford it, iron short swords/silver war hammers (silver is good for war hammer but bad for swords, iron is good for both but silver is better for hammers)
In a year you have 2 legendary dwarves whom will generally slaughter everything. Adding some metal armor helps also. To give you an idea, just these 2 will take out a 40 strong goblin siege without much trouble (also fun to watch!) if given the time to train (spar)
Do NOT add more dwarves to their squad. You're best off with 7x 2 man squads than 7x 10 man squads. Once they hit legendary no reason why not to chuck em all together.
There is something about setting training for 5 sets of 2x dwarves in one military squad, but i've tried to and it is no where near as effective as putting a new squad for each pair of dwarves.
use therapist to find the ones best for military a 60% dwarf for a weapon skill will hit legendary with a similar training partner in roughly 2 years.