Some general rules that can be applied to all types of shrubs are:

Always prune back to a lateral branch or shoot. Do not leave stubs or sticks.

You are trying to reflect the growing habit of each plant. Avoid shaping the plant into geometric forms. Different plants have different growing forms.

Hand pruners and loppers can help you correctly prune plants. Shearing plants with clippers is only done to a small number of plants, such as Yews (Taxus), Boxwood (Buxus), Japanese Holly (Ilex Cremata), Burning Bush (Euonymus) and Hemlock (Tsuga) in some cases. It is imperative when shearing these plants to step back afterwards and hand prune to eliminate any look of poor ends and damaged leaves. You should step back often to view the plant you are pruning to better see the results of your cuts.

After pruning a plant correctly you should see the plant in its reduced normal state without bare stubs, frayed ends and round forms. When correctly pruned, plants will look better, but is should be subtle since you are making proper cuts that are "hidden" by the branches that remain. Proper pruning takes patience and time, but it is well worth it.