When you are out looking to meet girls the most important thing to do is to play the odds. And don't do the things that turn girls off. The object here is to eliminate the things that can cause women to eliminate you.
The first thing you should do is quit smoking. Now, I realize that is difficult, but it is a must. Smoking is the one single thing that will turn away women more than anything else. Sure, a lot of women don't care, but some of the ones you might be most interested in will care (I know this from experience).
For God's sake, clean yourself up a little bit. Shave on a regular basis, and don't skip showers. In general you should try and be as clean as possible. No one is going to turn you down because you are too clean, (but when confronted with 2 otherwise identical guys girls are going to pick the one without the taco stain on his shirt every time).
You should avoid tattoos and body piercings at all cost. There isn't much you can do about tattoos that you already have, but body piercings can simply be removed. I challenge you to find a woman who will refuse to date you because you don't have any of these. I also guarantee you won't have to look far to find one who will refuse you for having them though.
You should strive to have normal looking hair. Any strange haircuts are going to drive away more women than they attract. Don't shave your head, but don't grow six or more inches of hair either. Medium to short haircuts will be seen as the most attractive by the majority of women. And no matter what you do, do not color your hair, leave it alone, it came that way for a reason.
Work on that body of yours a little bit (or stop working on it so much if you look like one of those guys in the muscle magazines). Get used to doing a little bit of physical activity, it will be good for you, and will help you build a better-looking body. This works for guys of all sizes.
Do you say the words fuck, shit, and cunt to the teller at the bank? Do you use the phrase "Big Floppy Donkey Dick" when speaking with clients? You don't? Those people aren't even important and you watch your language around them. So why are you spouting four letter words in front of a women that you may someday marry? Curb your potty mouth. This is not hard. My ex-girlfriend Katie asked me six months into our relationship if I ever curse (I curse all the time in front of friends), because in the six months we had been together I had never once cursed in front of her (she proceeded to make me say one, just to see if I could).
Try and buy a convertible, everybody seems to look more attractive in one. (The guy driving the 1985 Chrysler Lebaron convertible is going to get checked out ten times as much as the guy with the brand new Honda). If a convertible isn't a possibility, then at least keep your car clean.
One of the best ways to attract women is to be seen with attractive women. You don't need to know why this works, just trust me, it really does work. Read a book on psychology if you want to understand why it works.
Lastly, you should try your hardest to put yourself into a natural alpha male role. This may require completely changing your group of friends, but it will be worth it. Find a group that you can be the leader of, and lead it. You should also try your very best not to be the least attractive guy in your group of friends. Think about it this way, have you ever been out with the guys, and seen a group of women and said, "Whoa dude, I got dibs on the ugly one!"? Of course you haven't, so don't be the ugly one. Beauty can be very relative at times, a person of average looks will be completely ignored (as far as mating goes), when surrounded by beautiful people, but replace those beautiful people with unattractive ones, and all of a sudden that person has become very attractive. The entire last two paragraphs can basically be summed up by saying, surround yourself with beautiful women, and ugly men.
Now you need to practice a bit of rejection yourself. Stop going for the most attractive woman in any given group. There are several reasons for this, the first is that you are probably wasting your time, she probably has a boyfriend (and is probably horrible in bed, and in relationships, I don't need to go into detail, there are already many nodes on that subject). Secondly, once the "Alpha Female" of the group turns you away, it is difficult to immediately try to pick up the next in line.
If you are shy or fear rejection you should practice trying to pick up girls that are not as attractive as you would like. They are much more likely to be single and interested, plus you might fall in love with one of your practice girls, (like Jim did in American Pie 2).
Don't forget to let me know how it all turns out.
Be sure and continue reading to see a few other great takes on meeting girls from several other people. They are more right than I could ever be. What I wrote here was pretty much a guide on how to meet the girls that I like. Of course, your mileage may vary.