I think directness is usually the best way. That's how I've always been, and it's actually served me very well.
However, there is a certain way to be direct. Perhaps, when discussing anal sex, for example, the best phrasing is not
"I wanna fuck you in the poop tube and cum in your butt."
and you may find something like
"I've been doing some reading about, er, 'alternative' intercourse, and, I have to admit, it's kind of interesting. What do you think about it?"
more conducive to... well, cumming in her butt.
