H'ok! *cracks knuckles*
With a quick check of your profile, I see that you are male. That's important because typical flirting techniques don't cross gender lines very nicely. I'm also assuming you are trying to attract a female. If I'm wrong, just ignore everything I'm about to say. I'm not familiar with gay flirting customs but I'm sure they aren't that different from stereotypical heterosexual traditions. We're all human after all.
Also I find it prudent to note that there is no sure-fire-never-fail-100%-guaranteed method of flirting. It just doesn't work that way. For things to click on both ends, 3 things have to occur:
1. You have to capture the person's interest. There are many ways of doing this, and quite often it's not necessarily what you said or how you look. It's usually the little things like your laugh or your smile. These are mostly things beyond your control, so don't openly try to be interesting. It's obvious and quite often has the opposite effect.
2. The person has to be attracted to you. Ok this is probably the scariest part. In order to be successful in this area, follow this general rule. Before you go out to a social gathering or where ever you plan on picking up chicks, shower, comb your hair into preferred style, pick a nice clean outfit and make sure it's not wrinkled or stained, brush your teeth and then forget about it. "WHAT?!" Yea, forget about it. "Well what if I'm a girl and I must check my make up and make sure my blouse still looks good and adjust my hair and.." No forget about it. And I don't mean let yourself gradually become messy looking over the course of the evening. JUST STOP WORRYING ABOUT IT! People always get so worked up about how they look and their body image and they get so insecure and that's just not attractive! There is someone out there for everyone. Believe me. If you think you're ugly or fat or just strange looking, I promise you there are uglier, fatter, weirder looking people who are happily married. Confidence is attractive. A sense of humour is attractive. Have lots of interesting and thought-provoking things to say is attractive. And hey if you're drop dead gorgeous, well that's just a bonus-but not essential.
3. You have to make a move. People argue this a lot. Generally it is believed that men always have to make the first move. Cosmopolitan magazine polled a bunch of men and found them to be almost unanimous in their belief that men must make the first move, and that women just seem desperate if they make the first move. I don't buy that. I think all is fair in love and war and love especially. It's a level playing field, especially this early in the game, so if you are interested and engaged in a person's company make a move! It's always funny to watch young teenagers try to flirt because both parties are too afraid to make a move. Making a move isn't complicated either. There are varying levels and usually you start out with a lower tier move such as the infamous arm touch. "Hahahaha that was a really good joke, Steve! while at the same time reaching out and touching their arm lightly and briefly to place emphasis on "good". Intentionally touching someone (obviously in a non-invaisive non-creepy way) sends all kinds of subconscious signals so it's a good way to let the person know that you are interested. And letting them know that you are interested is important, because it makes them feel more comfortable letting you know that they are interested as well. After a few of these lower tier moves are successful, you usually go for a more direct approach of say... suggesting to hang out another time in the near future or the exchanging of phone numbers. Some people think this is too much for the first time they meet someone but honestly how are you going to keep in contact?
Learn to pick up on signals. If someone seems preoccupied when you're talking to them, or they make up excuses why they can't hang out with you later or give you their number, they've probably picked up on the fact that you are interested and they themselves are not. And hey, let's face it. It's going to happen. Don't let it get you down. 95% of the time, it's something to do with them and not you. Maybe they are already in a relationship, or maybe they just aren't interested in one. Maybe they're in a bad mood. Maybe there's something stuck in your teeth. Try not to feel sad over it too much. Clearly they aren't your type, and even if they did agree to go out with you and be your girlfriend, you wouldn't be happy, because they wouldn't be happy. Move on to the next person-there are always going to be more people.
And lastly, lose the inhibitions. You should always ask yourself "what's the worst that could happen?" Let's consider this for a moment. They could say no to coffee. That's kind of disappointing. They could say no to coffee and laugh in your face. Well that's pretty insulting. That's makes you feel kinda shitty for a while. They could say no, laugh in your face, and then tell all their friends so that they can all get together and laugh about you in the corner. Well that just plain sucks ass. But put it into perspective. Was that the worst thing in the world? I've been hit by a car and that was worse then getting rejected by a boy. I know someone who had to get a kidney removed and has to get dialysis all the time. That's a very unfortunate fate and if they could trade getting rejected by some girl and laughed at by her friends and still have their other kidney they'd gladly take it. What about that guy in the Mummy movie who got eaten alive by giant scarab beetles? Don't fear rejection. There are worse things in the world and if someone makes you feel bad for taking an interest in them then it just goes to show you and everyone else in the room what an asshole they are and be grateful you dodged that bullet because who would want to be friends with them?