Fancy Feast, burlesque performer
Casual sex does not mean sex where you are not allowed to talk. I hear that a lot of women are especially afraid to assert themselves in casual settings. I really don't get this mentality. After all, if you've only known a person for a couple of hours, why assume they know what you like in bed? Phrases that help get the conversation started: I really want to take you home and do x with you, but I don't feel like doing y. Does that work for you? Or, can I show you something that gets me off? If all you're doing is meeting up for sex, make sure you're having the kind of sex you want. Otherwise, what's the point?
The other advice I wish people would give and take more often is to be kind. People think that if they act too sweet or nice, their intended fling will take it the wrong way, so people wind up being inconsiderate or cold. Be open, be clear, be polite! Something like, "I'm just looking to hook up for a night"—then say please and thank you and get them a glass of water, dammit.