Pruning in the fall should be kept limited.
Pruning generates new growth which may not have time to harden off before Winter.
The one exception is the 3 D's: dead, damaged or diseased.
No matter what time of the year you spot one of the 3-D's, You should remove those branches right away.
Late summer is a great time to prune (shear) evergreens and broadleaf evergreens because it gives the tender foliage ( that you exposed during pruning) time to harden off. If you prune them too late the tender growth will burn & turn an ugly brown color which if it rebounds at all, takes a very long time to green up again. Examples of this are Boxwood and Spruce hedges.
Fruit Trees and Crabapples are best pruned in the Winter. March is a great month to do this as it can coincide with your dormant spray program. Dormant Spray kits can be purchased at Oceanview Garden Centre.Shrubs that bloom late in the year and that bloom on new wood or the current seasons growth, such as Hydrangeas & Caryopteris can be pruned in the fall as long as you do it late enough so not to generate new growth.
Most other flowering shrubs should be pruned right after they flower which is spring and early summer.
This give the shrub time to produce the next years flower buds. If you prune them too late it doesn't necessarily hurt the plant but you sacrifice the next years flowers.
A few examples would be Forysythia, Rhododendron, Weigela and Lilac. However when flowering shrubs get overgrown, gangly, thick and unsightly, wait till the leaves drop so you can see what you are cutting and remove no more than one third of the oldest branches. cut them near ground level, as these old branches are basically useless and prevent light from getting in and restrict air circulation. Do not snip back the branches that are left as they carry your flowers for next year.
This is called rejuvenation pruning and fall is a great time to do this. Wait till the leaves drop so you can see what you are cutting.