I think that so much of his fouls are because he is tentative. Look at Joel. Houston games excluded, he hasn't really been in much foul trouble at all this year. Maybe I just don't notice it because I'm always like, "Cool, now we get to see Oden," but I don't think so. But what does Joel do to not get fouls? He still plays pretty aggressive and gets quite a few blocks. I think he just knows where he's going, where he needs to be to get in the right position, and is very focused on his positions.
Greg hasn't learned that yet, and trust me, he will. But when he's playing with 5 fouls he, like Joel, is concentrating on being in the right positions to not draw a foul. Pretty soon he, like Joel, will just have that as second nature. He won't be able to avoid all fouls, obviously, but he'll learn to put himself in positions to not draw nearly as many.
I can't wait to watch him grow into a great player.