Physically, I like them to be super-skinny. It's just this thing I have. I dig really thin guys. I'm not the thinnest girl in the world, but I've generally found that a good portion of skinny men are not attracted to thin girls...so this works in my favor
As for hair type, etc...I like dark curly hair, dark eyes (brown or blue), and I REALLY have a thing for big noses. Strange, I know.
Mentally I want someone intelligent. Really intelligent. I'm generally attracted to smart engineers, scientists and the like as it compliments my own "liberal arts" intelligence.
Emotionally I want someone who is there for me--someone who is my friend as well as my lover and who will listen when I need them to. I want someone who understands that sometimes I might need him more than others--I certainly have the power to stand on my own two feet but that doesn't mean I want to do it all the time.