Looks are the first thing I notice, but personality is what keeps me interested or tells me to say "next!".
I like long hair on a girl, pretty face and big bright eyes, small bust, flat tummy and a round butt.
What makes her special is a great sense of humor, and generally being fun to be with, while still being able to have deep intellectual or philosphical discussions about life, the universe, and everything.
That being said, a girl who meets the personality requirements doesn't have to even remotely match the physical requirements for a long term relationship, my ex only met half of them, and I married her.
In general, I think most people, guy or girl, are looking for some experience of pleasure from looking at or interacting with the other person. So, what kinds of things cause that pleasure? Well, different things are pleasureable for different people. Some things are pleasureable for many people.
Some things you cannot control, but others you can. You can eat well, workout regularly, dress well, etc. You can smile, you can check guys out, you can smile when they check you out, you can be friendly (friendliness is basically about pleasuring another person via social interaction, but not too much!).
Those are some of the things you can do to increase the chances of making contact with guys.