Obviously, being some cad's side action is always a sucker's game, but if you're going to do it, do it right.

Choose Carefully.

It's bad enough that you're "dating" a married guy, but when you start sleeping with someone who's in a position of authority over you, you're screwing yourself twice. Every good grade will be chalked up to your romance with the professor and every promotion credited to time served on your back. Don't kid yourself into thinking that no one in your class or office knows, because people aren't blind and you're not that slick.

Don't Go Home With Him.

Maybe he's too cheap to pay for a hotel room, could be he secretly wants to get caught ... then again, maybe he's just a sociopath. I can't even tell you how many times I've heard about a married dude bringing his girlfriend back to the house he shares with his wife and kids-usually when everyone's out of town, but not always. David Letterman even took his mistress on vacation with his family! Whatever his motivation, resist. You're already hurting this woman by banging her husband; at least have the decency to stay out of the bed they share.

Accept That You're #2 And Will Often Be Treated As Such.

Married guys will tell you a lot of things in their quest to bed you. That they haven't slept with their [insert bitchy descriptor here] wives for [insert insanely long period of time here] and that they're only staying together for the [kids/finances/etc.]. You need to know going in that you will always come second. (Or third. Or fourth.) Sure, you might get expensive gifts, but you'll also be spending nearly every holiday by your lonesome, you'll never meet his friends, and plans will be canceled on a moment's notice if something more important (i.e., anything) comes up.

You're Not His First ...

A cheat and a liar-who would've guessed?!

... And Probably Won't Be His Last.

Most guys don't leave their wives for the women they're seeing on the side. Yes, I know-your grand passion is "different." Snort. But what if he actually does splinter the family into bits and make a (semi) honest woman out of you? According to the website Beyond Affairs, only three percent of men marry their affair partners, and out of those only three percent of those marriages last. And why would they? You're committing to a relationship that was built on lies and deceit.

On second thought, maybe you want to rethink this whole "other woman" thing?