My rules for going to the bar:
1) Never look slovenly. I've had a gf for 3 years, but if you look like a bum you're going to have a bad time (unless you get hammered).
2) Im 24, when I was 21 it was okay to get so drunk you'd get thrown out. I realize if you get so drunk you can't walk straight you will probably have a bad time/bad morning.
3) Never be afraid to dance. Getting a girl you've never met but think is cute to dance with you is a priceless victory. If you dance with cute girls, you're gonna have a good time.
4) Never take rejection you receive because you took point number three seriously. If you take yourself too seriously you're gonna have a bad time.
5) Never go without a buddy if you can help it. If you go alone you have a greater chance of having a bad time.
6) Never get too centered on "going to a certain bar" after 12. If you spend half your time in cabs, you're gonna have a bad time.
7) If looking to hookup, find some after hours. If you go to an afterhours you're gonna have a good time.

Long Island iced teas are like martinis and like hands. If you have more than two, you're gonna have a bad time (assuming your bartender doesn't suck)
9) Building off of point 8, and the astute poster above me, stick to beer or 1 liquor drinks. I prefer the best draft beer or 7 and 7s. If you stick to easy drinks or beer you're gonna have a good time.
10) There is nothing wrong with shots. Especially if someone else is buying them. But if someone buys you a shot, always buy a round yourself. If you stick to karma, you're gonna have a good time.
11) Be nice to staff and try to limit yourself to dealing with 1 bartender. If you tip every drink (and overtip the first couple), bartenders will serve you faster, and usually buy one back. If you're good to the staff, you're gonna have a good time.
12) Never bring nice jackets you're going to take off to the bar. You very well could lose it if there isn't a coat check, and even if there is. If you lose your jacket you're gonna have a bad time.
Thats all for now.