I'm a terrible Renekton. I'm gonna camp your thread and hope I get tips, too.
I think most of my problem is that I don't play toplane, and I don't know how to lane against toplaners. This might sound silly, but fighting that Wu in a teamfight later in the game is ten times different from playing against him in lane.
I think I start w for the stun, then go e, then q. I think, ideally, your combo should have you e'ing in, w for stun, and then maybe q if there's time? E back out if you need to. Make sure you hit your opponent with e so you get to use it twice.
I build bruiser... Uh, merc treads, I think hydra and some other damage item, then tank all the way. Spirit visage seems to be good?
His q is super for waveclear and sustain. Q all the things.
I haven't gotten the hang of the fury mechanic.