Proactive. I rarely start a game without a goal.
For migrants I generally give them all a "Peon" role, and then assign them specific tasks(or roles) as I need them.
Looking through, this seems to be a popular attitude. Have a goal and unless the migrant is a god in something, reasign them.
However I am a bit crap myself at protecting myself from the annoying strange mood. I say annoying because i never seem to get happy results.
The main reason I don't is that my workshops are focused into what I need, now what I have skills for.
So when the strange mood kicks in and I am not paying attention, the guy who is dabbling in about 5 different skills doesnt have the building he needs and without me setting something up he will flip out.
If however I had catered for him when he arrived, perhaps I could have avoided that.
I now have to create a workshop in my workshop pool, once I get going for EVERY workshop.. so the problem should never happen there.
I did however take a different tact recently and for anyone that was a weak skill, I put them into the pleb role (whatever busy work i needed) but otherwise if they had a juicy skill, I immediately found use for them.
Before I knew it, I had 5 Beekeepers (3 that appeared in the same wave) running a thriving beekeeper farm. I was making mead exclusively (i know, not good for happiness with no variation but it felt good with the theme) and were it not for my fisherman turning into a necromancer, I was hoping to setup an entire empire on bees!
I do like this approach though because you go into the embark with minimal skills, with no goal and let the randomness to kick in and flow with it. So all of your guys want to be mechanics.. time to make the most trapped and suped up fortress possible MUAHHHAAAAHAHA