I can't speak for others, and there are some great newbie mistakes listed here. Mine are too numerous to count

but here are my top three newbie f*ckups:
1. Being overly nervous/anxious/wired. Easy to do for a first timer. You forget that hey...it's just sex. The only difference is that it is easy to find and the game is simpler...pay, play, say hasta luego.
2. Being intoxicated. Whether from the altitude, lack of sleep, being wired (see #1 above) or whatever, I find it a whole lot easier to get drunk off my ass in S.J. If you do that, you're literally pissing away the chance for good sex. I try to stay teetotal during the day, then drink after the sun has long gone over the yardarm. And BTW, not drinking makes my yardarm (okay, incharm) work better.
3. Not staying within budget. This involves several mistakes mentioned earlier in this thread. Spending too much for a chica's services (i.e. no negotiation), taking chicas you're really not into, overtipping (yes, I do it too), and not being smart about where/what to eat can all negatively affect one's budget.
Fortunately, I have avoided many common newbie mistakes, thanks to CRT and the direct counsel of my CRT brothers. It took me awhile to find my pace and to really be able to work things to my benefit, but fortunately there's all kinds of help here for those who will listen.
