Remove branches that are crossing each other and rubbing. Select the weakest of the two branches, usually the oldest, and cut it at a node at a 45-degree angle.
Remove older branches from the bush by cutting them as close to a node as possible, using clean pruning shears. Old branches do not produce flowers as vigorously as young ones; removing old branches renews the plant.
Thin out 1/3 of all the oldest branches if the shrub is overgrown.