Coolness is a side effect of doing awesome things just because you feel like doing them. It's kinda like falling asleep, or swimming--the harder you try, the more you thrash around, and the worse you'll do at it. Wanting to be cool is the same as saying, "I desperately care what other people think about me, to an extent where it is a detriment to me." Paradoxically, people respect you more when you don't seem to need their respect.
So, how do you make yourself less needy for respect? You can only make yourself cooler by forcing yourself to do things that bring you out of your comfort zone. Learning to deal with the embarrassment of other people's scorn is the only way you'll learn how to stop caring about what they think. Be the first one out onto the dance floor; ask that girl out; ask for that raise; wear something hideous in public; make more eye contact, whatever.
Cool people do what they want to do; uncool people only do what they think other people want them to do.