In my experience, girls like the following:
NB: Before anyone judges me, I am a total hypocrite as I don't follow all of the below points, but I'm trying to and will hopefully succeed one day!
1) Compatible personality - You've got to show that you can get along with her. If you can make her laugh, you're doing great. You've got to feel comfortable around her and vice versa. Moreover, there's got to be some energy between the both of you. If she's staring blankly at you or doesn't seem to be interested in you, then either she isn't, or you haven't projected yourself well enough.
2) Confidence - So cliché to say but it's absolutely true. Girls don't like the guys who sit in the corner and twiddle their thumbs. They like a robust grounding and can-do attitude.
3) Be Yourself - Again, very cliché to say, and again it's entirely true. I'm no expert, but every girl I've ever been with said that she liked me for my uniqueness. So show them what you've got. (No, no that thing, I mean you as a person)
4) Keep in good shape. I wouldn't say that looks matter the most. See, you're dealt with a hand and that's it. It's in your genetics or whatever you want to say to justify your appearance. The critical point is, there's no such thing as 'ugly'. It's a subjective term. You've got to take care of your body the best you can, keep it lean and eat well and you will look and feel more vibrant, and subsequently attract more women. One girl's reject is another girl's dream, so don't ever write yourself off.
5) Be nice - (Did I mention cliché, anyone?) Girls like nice guys from my experience. Be kind, don't favourite anyone especially, just do good deeds when and where you can and you'll be surprised how much it carries over in your relationships with your friends, family and girls to come. You'll feel better and this will show when the time comes.
6) Eat rejection - If you ask a girl out (because you like her, quantity of asks <<<< quality of asks) and she isn't interested, then that's her loss, as far as you're concerned. Take it like a man and don't go crying home. Get out there, meet some nice girls. You may already know some. If there's one special to you, get yourself ready with the aforementioned points and go and ask her if you want to get a drink.
The people that find it difficult to get girls are the ones who don't try. And I don't mean that you or me or anyone else should just go out there and 'cold call'. I'm talking about meaningful pursuits. Prepare yourself like you would for an exam or an interview even if it sounds corny and you'll see what happens.
Anyway, best of luck! Have a good one.