There's a lot of confusion over when and how much to prune your shrubs. For spring flowering plants like azaleas, this is the optimum time to gently shape them. (Ignore summer-blooming plants until fall or winter, or you'll prevent the growth of flowers.) The general rule of thumb: Wait until the blooms have faded and you have signs of healthy new growth. Then cut lengths of branches for a natural, rounded looking plant. Beware of over-pruning, which can shock and damage the growth.
Related: 8 Reasons to Love Azaleas