The best advice I got before trying shrooms was: Whatever happens, whatever you see or feel, remember that it's just the drugs. No matter what you feel like, it will end. It's just the drugs.

Works for other drugs too. If you get scared or emotionally uncomfortable, remind yourself that it's just the drugs.

Was especially handy when coming down from a combination of MDMA and coke. Not a good hangover to go through on your own.