Well, my plan of attack as soon as any migrant wave shows up is to pause the game and fire up Dwarf Therapist. It has a nifty feature that lets you sort by migration wave, which puts all the midgets migrants at the bottom of the list. And you can do this as soon as the first one hits the map edge rather then waiting for all of them to appear.
- Anyone with fishing labors gets them turned off.
- Anyone with wood cutting or hunting or mining has shown up with a weapon and I don't turn those off until they get close to or inside the fort. Don't disable those 3 labors until the dwarf is on the map or within the fort, or they'll drop their weapon out in the invisible no-man's land of the map edge.
- Anyone who has a skill, in a skill-based industry that I care about, who is only dabbling when I already have a master/legendary dwarf, gets that skill turned off. This is engravers, leatherworkers, clothiers, weapon/armor smiths, masons, mechanics, cooks, brewers, planters. Unless I'm in a period where I need more bodies for a profession and don't care about skill level.
- I look for dwarves that have very long lists of skills. Such as 15-25 different skills, all at low levels. Those get investigated a bit more closely for signs of vampirism.
Once they get inside, they don't do much except haul for a while, until I need to expand an industry or setup a permanent military squad. Most of them get all the junk skills turned on such as milling, plant processing, spinning, weaving, wood burning, lye making, in the hopes that they will eventually become useful members of society.