Okay, let me add to refractor's post and kind of bolster it with some things that go right along with it.
Looks AREN'T everything, but, as refractor said, it gets your foot in the door.
Being nice and courteous is one of the most important first impressions, next to personality (but personality can be a continuing impression as there are always new levels). Be sure to be a gentleman. I have a wicked sense of humor and snap off harsh comments that I think are funny and about every girl I've met and am friends with hated that about me when they first knew me, but then I always did gentlemanly things like opened doors for them, held their books, and they just started to love me and understand and even LIKE my sense of humor after that.
Be yourself is the biggest one. Why would you want to be anyone else and feel awkward? Then you'd always have to put up this guise and never really be who you should be around the one that's supposed to be closest to you. This friend of mine, I'm myself with her all the time. I can talk about anything with her and she can do the same with me! It's so great to have a friend like that, and it's really great that it's nothing more than friendship (although we've actually discussed that two or three times). I wouldn't change the parameters of our relationship for anything right now which is great.
Relationships that "just happen" are the best on earth. I wish it could always "just happen" because it's so much easier and more fun.
Smiling a lot to attract women, no not really. But don't look SAD! You have to look content, secure, stable, and confident. Let me give you an example. If you've got trouble with acne, don't think about the acne because then even a smile will be fake and give way to insecurity. Girls are like dogs ... err.. in the way that they both can smell fear and insecurity (Pam, Kiera, you know what I mean

, I'm not calling girls dogs). If you look like you've got no problems in the world then that's a good thing.
ALL of refractor's advice was EXCELLENT! Pay heed
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Village Ideot, Our school does that too. All of the girls I know got me on the top 5 of their list (out of 20). And the three girls I'm friends with the most all got me on the top of their list. They kind of talked to me less after that but smiled at me more, which says even more. But that was so funny the day those were released.
We had a valentine's day dance. 60 people went to it. I can only imagine what they were thinking when they bought those tickets.