Remember to keep your pruners and loppers sharp. Good pruners use bypass blades rather than anvil type. Anvils have only one cutting blade and one flat blade which can result in "smashing" the plant material. Sterilize the pruners or loppers between each plant and after cutting off any diseased plant material. Use a 10% bleach solution (1 part bleach, 9 parts water) or disinfectant bathroom cleaner.
What and When to prune
According to UC's Backyard Orchard website, "the optimum time of year to prune fruit trees is the dormant season, December, January (best) and until the middle of February." Apricots are the exception for pruning in January; they should be pruned in the summer after harvest. If you properly prune and care for fruit trees you will get the highest yield of fruit. A good rule of thumb is to prune plum, pluot, apple, and pear trees 15-20%; and peaches 50%.
Deciduous trees can be pruned anytime during their dormant season (in winter). Prune deciduous species, such as Western spice bush, creek dogwood, Western mock orange, red-bud, maples and deciduous oaks.
Do not prune apricot and cherry trees in winter because they are susceptible to Eutypa dieback. The best time to prune them is late August before the rainy season starts.
While you're outside pruning, remember to pick up any rotting fruit on the ground at the same time.
Make your cuts with care in order to direct the growth for next year. Check the tree for crossing branches, broken branches, diseased wood, and old leaves and fruits. Clean out suckers, light branches, and trim the branches that grow vertically. After that, you can start to shape the tree with cuts for form and fruit production. To have an open tree with good air circulation, make cuts above outward-facing nodes. Choose nodes where you want new growth and make a cut about 1/4" above, refer to the image below.