Well for me, I have observed that a girl's smile is the first thing that catches my eyes. Especially, when that smile is genuine.
As for personality, I like someone who's really friendly, approachable, funny, easy-going, and independent. Someone whom I can take to a business/social function or even at a party and be able to handle on her own.
As for attitude, I like someone who's responsible, open-minded, eager to learn and explore, and understanding. I'd like someone who could understand my (work) responsibilities and would stand unwavering by my side.