For ladies, off the top of my head:
Make sure your phone is fully charged before you leave the house.
Drink water before, during, and after. If possible drink more water than alcohol.
The reason why you don't feel drunk is because you're standing up and dancing and moving around. Stick to your limits if you already know them; going overboard just means you'll feel twice as wasted and miserable when you get home.
Going to the club is the same as being a mom of 3 kids and taking them to the zoo. Bring a big mom purse with a water bottle, granola bars, motion sickness pills, Tylenol, mints, hair ties, pads, tampons, condoms, comfortable shoes to change into, a light sweater / cardigan, portable phone charger (if you don't have one then get one), and anything else you think a mom should carry with her. Leave your purse at coat check and just keep a little wristlet with your phone, ID, cash, and maybe lipstick for touchups when you get on the floor.
Don't try to hold a real conversation anyone. There is an 80% chance they can't hear you. When you do talk, speak low and loud from your stomach.
If you put down your drink even for 5 seconds don't you dare even think about picking it up and drinking from it. If you want to dress like a total whore by all means go it, but do not wear your 4-inch stilletos unless you're willing to commit to them. Doesn't matter how trashed you are or how much your feet hurt, you are not taking them off and going barefoot. If you really can't take it then go change into the comfortable flats you were smart enough to bring with you.
Lines don't mean shit. If you want a drink, lean over the counter of the bar with cash visibly in your hand and make yourself noticed.
If a girl is crying in the bathroom you ask her what's wrong and try to help. If you see a girl getting creeped you go dance with her until the guy leaves. If a girl needs a hair tie, pad, tampon, or a hug you give it to her no questions asked.
Have fun.