#3 Proper precautions. Here’s a huge mistake for a one night stand: Not using protection. Think about it. You’ve gone home with someone you’ve only just met. The odds are that they’ve done the same thing recently with someone else, possibly multiple times. And they’re willing to have sex with you without a condom, so you should assume they didn’t use one last time either.
Unprotected sex on a one night stand, or in general outside of a monogamous relationship, is just a terrible idea. There are plenty of nasty diseases you can get from unsafe sex, some that last a lifetime. And besides that, next time you’re taking someone home from the bar, look at them and ask yourself if you want them to be the mother or father of your child… Yeah, didn’t think so. Wrap it up.