Here's a comprehensive pruning guide, which includes hedges, pruning tips and tools, a glossary, and examples of shrubs which bloom on last year's growth and those that bloom on the current season's growth. Before you prune, know which category your shrub grows in. There's also advice on what not to do, such as topping--and in the case of crape myrtles--crape murder, which is very common in our area. Link: Proper Pruning Techniques Aggie Horticulture
Sparkle note: If you drag a treat from the box, and click on it again, Sparkle will jump up and catch it.