Normally I like to mix it up and add variety to my sims. And for each sim, I usually pick about 2 salient traits that form the core of their personality. I usually have their physical appearance and clothing tailored, although sometimes I might do looks before personality first (like what I did with Lana Lavender, which admittedly, is mostly me amusing myself with her backstory).
I think I've pretty much settled on my twin's personality and hair colors at this point. All that's left is to make them tomorrow and to flesh them out. :D
