There are a ton of threads covering this already (use the search function). But I'm kinda bored right now, so ....
1) Don't be one of those fucking poseurs who does dinky little lines that numb your nose and nothing more. Lay out a good .15-.25gs per line. Trust me.
2) Have something ready for the comedow. Alcohol, pot, benzos .... if you do more than a couple of lines, you'll have a comedown to face and it's not pleasant if you're unaided.
3) Regardless of what anyone says, 'tis quite possible to refrain from doing whatever you get in one sitting. Take a killer rail or two and then put it away. The only thing going on a binge does is kill your wallet and leave you feeling like shit the next day. Just tell yourself "i'm fiendin, i'll be fine," and you will be.
4) Never, ever again call it "chachi" or "hooha." Such slang is laughable. "Blow," "snow," and "cola" are all acceptable alternatives.