How do you make a guy work for it?

Okay, so I've been talking to this guy for a while now, and he (recently) will drop subtle hints that he wants us to have sex. I was talking about it with my friends and they advised that I should make him "work for it." 
I honestly don't know how to do that, and while I know I am ready to have sex and etc. (I don't care if it's casual) I don't want it to seem like I'm "easy."
Any tips?