The fact that you have a self-published book is worthy of an A+ in my mind.

I've entered several challenges over on Vocal with no luck. Sometimes I wonder what the heck they were looking for when I read the winning entries, and other times I am in awe of the talent. My philosophy is that you've gotta be in to win.

I'd just go for it - if you don't win, at least you gave it a shot.