Easiest thing to do is really just ask him. Every guy thinks of things he wishes his girl would do. Ask him to be honest about it, make sure he knows you won't hold it against him, and tell him you really want to try some new things to make it more enjoyable for him.
If you were asking me, I'd say get freaky. Lick him places. Suck his earlobe a little. Kiss his balls. Slap his rear. Wrap your legs around him when he's pushing in.
Have you gone to the bookstore and browse the sexuality section? You will be amazed at the number of books that have hundreds of positions in them, or articles on how to spice things up...also, you can read one of those men magazines and look at articles there that go over what men want in bed etc. You can go to the library and look at the past editions and you will find tons of things to do. :) I can't think of the magazine names...I think HQ? or FM?