Then, when you've started talking to someone, spell out what you mean. "I’m all for the direct approach — why waste anyone’s time if you know what you want?" Dr. Morse says. That means being super clear about what you want to get out of this arrangement. Don't just tell your potential fwb that you want casual sex , explain what casual sex means to you. Because friends with benefits might mean something totally different to you than it does to them. And you need to set ground rules before you start hooking up. Do you just want to have sex with this person and nothing else? Or is it okay for you to hang out as friends, too? Are you both going to be hooking up with other people as well? Are you going to hook up at your place or theirs? Are you both going to get tested for STIs before you have sex for the first time? ( You really should, cause safe sex is the best sex ).