The carpenter’s mantra, “measure twice, cut once,” also applies to pruning. With pruning it’s “evaluate twice, cut once.”
In other words, don’t cut until you’re sure that you’re cutting the right branches the right way. Less is often more. Bad cuts can be difficult to rectify so it’s important to know your plants, know how they respond to pruning and know what you’re trying to achieve.
Most garden experts define pruning as part art and part science. Pruning done properly requires a good eye and often a vision as you project what the outcome of your cuts will be. You need to be able to “see” what you want to achieve before you start pruning. Science involves how the growth of the plant will respond to your cuts. For example, a pruning cut in a particular direction will produce growth in direct response to the cut you make. That’s how we decide where and how to prune.
Proper pruning can be a daunting task — just knowing how and when can be confusing as it is based on the type of plant, the best time to prune that plant, and on what you’re trying to achieve.

Basic reasons to prune:

• to cut out dying, diseased or old unproductive wood


• to reduce or control the size of a plant


• to get larger blooms or larger fruit


• to remove crossing or rubbing branches or branches that are growing in an undesirable direction


• for aesthetics (can be formal or more naturalized)


• to reduce possible storm/wind damage

There are two primary types of pruning cuts. “Heading” refers to shortening a branch by cutting it back to a bud. Shortening a plant this way actually causes a burst of thick growth, which can defeat your original purpose. “Thinning” cuts involve removing a branch or stem at its point of origin — back to a larger branch, back to the trunk or sometimes back to the ground. This thins the plant and opens it up for improved health and a more natural appearance. Done properly, thinning cuts can also reduce the size of the plant.
There’s one other unfortunate possibility although I can’t recommend it. It’s the technique known as “whacking,” but let’s not go there.

As the leaves start to fall, it’s easier to evaluate the structure of each of your plants. The bare stems allow you to see what needs to be done to improve the structure and/or the look of the plant. Even though it’s recommended to prune spring and summer blooming plants right after they blossom, you can usually perform thinning cuts once the leaves fall. Heading cuts in the fall or winter will reduce the number of blooms for the following season so stick to the thinning cuts for now. Forsythias, hydrangeas, buddleias, cane roses and nandinas can all be thinned now if you remove entire branches and canes back to the point of origin. But remember, if you overdo it, you’ll sacrifice next season’s blooms and you’ll run the risk of cold damage on any new growth that you inadvertently encourage.
You can and should prune dying or diseased wood, crossed or rubbing branches any time that you see them, regardless of the season. For non-blooming plants, it’s generally best to prune when they are fully dormant, usually in January and February.

The Virginia Cooperative Extension is our best source for pruning guidelines. 

Per the cooperative extension’s recommendations, the following can be pruned in November and December:
Deciduous trees: Birch, Golden Raintree, Linden, Maple, Oak and Poplar
Evergreens: Arborvitae, Chamaecyparis, Deodora Cedar, Holly, Juniper and Leylands
Shrubs: Abelia, Beautyberry, Boxwood, Buddleia, Euyonomous, Nandina and Ligustrum.
Remember that the winter wildlife needs our help so if you have still have berries on any of these plants, you might postpone the fall pruning so the birds can enjoy the berries during the coldest months.