By pruning shrubs regularly (yearly, in most cases), you'll hold them to the size you want and keep them from becoming too dense (and then dying out in the center as a result). The pruning method you follow depends on the way the shrub grows ― from the base or from an established framework of branches. The appropriate technique for each is shown below.
New stems from the base
Most deciduous shrubs and some evergreen ones grow by producing new stems, or canes, from the plant's base. Keep these plants vigorous by periodically removing the oldest and weakest stems.
A framework of branches
Most evergreen shrubs and some deciduous ones form a permanent framework of branches. Often, the only pruning required is the removal of dead, damaged, diseased, or unattractively placed branches.
Some of the most popular garden shrubs, such as azalea, rhododendron, and pieris, require little or no pruning aside from deadheading (removing faded flowers before they can set seed). For all its simplicity, this job is an important one: failure to do it will greatly reduce the quantity of blossoms produced the next year.
To deadhead, snap off spent flower clusters between your thumb and index finger, as shown at left. Be careful not to damage growth buds just above the cluster.