A perfect place to start is to remove dead, diseased, or damaged stems as soon as you see them. Dead branches and stems attract harmful insects that increase the chance for disease.
Another great place to start is to remove branches that are rubbing together and upright shoots growing off the trunks.
By removing the dead or faded heads (deadheading) of flowers, the plant is able to put more energy into blooming, therefore improves growth.
If the plant develops bare stems at the base, remove the stem and it will force the plant to grow more compact.
By deadheading the flowers, the look of them will be significantly improved. It is also a good idea to deadhead the flowers if they are too leggy or starting to bend out from the middle of the plant.
A benefit of this is that most perennials will be able to push out another bloom cycle before deadheading again.
Deciduous Fruit Trees
Apples, crabapples, plums, peaches, cherries and pears should all be pruned in midwinter. This has been debated in the past due to removing some of the buds but the goal is to open the tree to more light and allow for a better crop of fruit rather that maximum bloom.
It is essential to prune a lot of fruit trees in winter because the plant is dormant therefore at less of a risk of bacterial disease.
Prune roses and climbers that bloom annually after they finish blooming.
There are several roses that bloom repeatedly. Prune these to your own custom shape and always remove damaged and diseased branches.
Shaped or Clipped Hedges
Buxus, privet and other shrubs are often trimmed to form a hedge. To form a wall or solid hedge, trimming several times when the new growth is coming through will make a big difference. It is essential not to have the top wider than the base as it will shade the lower branches.