[wonderbread]

Work yourself into it. Like you said your not used to this yet and so your not used to calling guys cute things.
I am sure he knows that you like him and all that. You don't have to jump into it and call him every name in the book. But guys do actually like to be called sexy and cute. I know a lot of guys that actually liked to be called that.
Just start small, if he smiles and you like it say. I love your smile. If you like what he is wearing tell him he looks good or sexy in it. Tell him things that suit him.
Tell him you like it when he calls you sweet things or say sweet things, that is a compliment in itself and most like to hear it.
When you two are together anywhere and aren't holding hands, just gently touch him on his leg if you two are sitting next to each other somewhere or lay your hand on his shoulder or wrap your arm around his shoulders. It is a sweet gesture and reassuring.