there is some great reference /inspiration in the contest and challenges section. one of my favs- http://boards.polycount.net/showthread.php?t=53731&page=4
Challenges are the best way to practice! Don't be affraid of posting your progress, feedbacks are really helpful! And that's a nice start BTW keep going ;)
I totally agree that joining challenges or competitions with a strict deadline drive my productivity. You can't procrastinate on those. Thanks for the post!