Looks (for girls) would have to be curvy, nice eyes, hair, etc. I find don't find guys particularly physically attractive at the best of times so I'm less picky about them as long as they aren't too much taller than me (being under 5' this does limit my options).
I'm a really crappy girlfriend so in terms of personality they couldn't be too emotionally needy but at the same time, ideally, they'd be prepared to give more than they receive. Intelligent, sense of humour, all that stuff. Preferably has the same sort of hobbies as me, I once dated someone who didn't really read much and I drove myself nuts trying to interest him in my favourite books. Either has the same sort of beliefs as me or is comfortable enough to talk or debate about them.