the best way is to be well informed. if you take a bunch of acid and go to a typical party, you're gonna be scared shitless. just make sure you're in a relaxed, comfortable environment. some people like to turn off phones. know how to talk yourself down from a panicked state, like "i'm just on a drug right now, and i know it's going to wear off." read some of the good and bad experiences on erowid so you know what to watch out for. and if a trip starts going in a direction you don't like, a change of scenery is always an idea.