You're getting pretty good.
I still see a lot of straight lines, but you're creeping up on it. Try using a small radius and right clicking the edges to rough them up a little. Remember, the shading is not a solid color. you don't need to worry about it looking jagged in-game. the jaggedness actually makes it look a lot more natural. Keep practicing. There's not really a way to teach the little subtleties. They have to be discovered for yourself. It's a little thing called style.
KF
Edit: A couple of examples to show more than I can write (explain)
http://www.fliggerty.com/phpBB3/gallery/image_page.php?album_id=66&image_id=271
http://www.fliggerty.com/phpBB3/gallery/image_page.php?album_id=66&image_id=272
Notice how the unshaded path looks squared and blocky? You can't even tell where the textures meet in the shaded shot.
That exterior is the one that got me promoted at TR.