See also: 10 Dating Deal-Breakers
Don't make promises you can't keep.
Sometimes, you tell a person what you think he/she wants to hear in order to close the deal on a one-night stand. The problem occurs when you cross that line from flirting/complimenting to making empty promises with no intention of keeping them. We've all made the mistake of telling a one-timer that we'll go on a date with him/her in the future, but there's a big difference between promising a single meal and telling him/her that the two of you are now in a committed relationship. We're pretty sure there are entire seasons of true crime shows (or as South Park called it, "informative murder porn") dedicated to people who would still be alive had they not lied about a relationship just to have a casual hook-up.
Know who the person is.
This is actually important in two different ways. For one, it's good to know the person's name in case he/she turns out to be a murderous psychopath (again, see: informative murder porn). More importantly, if you know a little bit about the person going into it, you may be able to tell how to appropriately handle the potentially complicated aftermath of the one-night stand. If he/she seems like someone who has some experience in the one-nighter department, he/she's a lot more likely to be gone by the time you wake up (or to provide a bottle of water for your trip home) than if he/she's some naive coed who happened to run into you while his/her parents were visiting the Grand Canyon.
Don't lie about the person.
Considering that you're reading this online, we're guessing you've heard of this thing called social media. One of the great (or terrible, depending on who you are) things about social media is that it means people have to work just a little bit harder to lie about what they've done. That includes one-night stands. We already know that you're going to tell your friends that the person was significantly more (or less) attractive than he/she actually was, but just keep in mind that it probably won't be that hard for them to find photos of your brief partner on Facebook/Twitter/Instagram after you describe him/her as "a solid 10" when he/she's more of "a flimsy six." Personally, we think it's better to say less and let them find out more for themselves than to talk a lot and get called out by all of our homies.