At trackdays I'll often see riders taking lines around the track that hurt their lap times, and jeopardize their safety. If you're not sure how to choose the best lines, you might want to check out an article I recently wrote for the MotorcycleAddicts e-zine, called "Using the Whole Track," where I share some ideas I've learned over the years:
http://www.motorcycleaddicts.org/learned-hard-way/12895-using-whole-track.html#post104444