LT40,
It's great that you're progressing in your flying!!! Unfortunately broken props are just part of training. That's just the facts of the matter. The best thing I can say is to just stock up so that you don't get grounded by a broken prop. You didn't say what brand of props you were using but I usually recommend that my students buy Master Airscrew props for when they are learning. I recommend these because they are usually the lowest priced props out there and they can take a pretty good amount of punishment without breaking. This doesn't mean that they won't break, but they'll better absorb those dings and dents that are just part of learning to fly.

Hope this helps

Ken