Apple (and pear) pruning is pretty intensive, especially if you want fruit. This is becasue the fruit spurs last about 20 years and apples grow with a lot of vigor. They also tend to produce a lot of dual branches and water spouts.
When cleaning up old apple orchards (we have some 50 year old trees here) I cut the dead branches out first. Then the broken ones and diseased ones. Then the water spouts (large branches that grow in one year with no fruit spurs on them). Then I cut out any redundant 'double' branches in parallel with another branch. Then I cut any branches that are growing back into the center of the tree from outside. Then I cut long branches back 30-90%, depending on length and size. I also cut any tiny branches less than the thickness of a pencil (be careful not to cut off fruit spurs that size), and cut all the suckers growing from the roots around the base of the trunk.
That done, I then start to cut for shape. Shape is highly variable. I use a central leader scaffold system and not a vase or umbrella system like in the days of old. The problem with central vase pruning is that you put a lot of loading stress on one central point in the tree. If any branches split (as they tend to do in storms, or when heavy with fruit) that opens/exposes the whole branching system at one central point in the tree. A central leader system has a leader that is selected as a center point. Limbs are left to grow from the central leader at various intervals separated by at least a few inches and growing in different directions. I also do espallier pruning on my new trees, but that is a different topic.
That being said, on old trees the shape may already be determined and there is not much you can do about the scaffolding system desired. Prune to the shape that grew or was pruned for before, or that is asthetic to your eye. Try to ballance the tree to give it shape and structure so that it can gather light and produce fruit. Cut long arching branches shorter to better hold fruit (or bears, in your case). Cut out dense clusters and try to encourage growth where there are wide openings. Cut any branches that are really low to the ground or bent to the ground, and I cut branches that are way up and too high to get fruit from, or that are disporportional to the rest of the tree.
Then look at the spur system. Spurs are the scaly stubs that will produce flowers and fruit. On apples, they live for up to 20 years. In an established apple orchard, the rule of thumb is to cut about 95% of all new growth and leave 5% to grow and create new spurs. New growth will usually be smooth and not woody. You can follow the new growth back to a short scaly section where the end of last years growth stopped, then follow that back another year. That section will have some fruit spurs that are starting to form. Usually by the 3rd year bark will start forming and the spurs will be more developed and longer. Back on old bark wood you will see longer developed fruit sprus all along the tree. Do not prune or knock these off! In the case oe pears, they tend to create branches that bed over and sag. These are OK if you like that look.
Lastly, timing of pruning is important. If you are pruning flowering crabapples or ornamentals wait until after they bloom to prune. Otherwise you are just cutting off all the flowers before they bloom. In the case of fruit trees, prune them before they bloom. Later in winter is better. Studies show that trees recover from pruning faster when done in February as opposed to December. Also diseases are usually less progressive later in winter than fall and they will have less time to attack and damage your trees before they begin to grow again if you prune them later.
Good luck. There are many pruning books out there that show and describe all of this stuff. But it takes a few years to get the ideas down and figure out what you want to do when pruning. I still get to a point where I am not sure if I want to prune more tree or not. Usually I will stop then and decide to go back in later or not, or wait and prune out a section the following year. Another trick I have found it to prune an older orchard over 2 years instead of one. Cut out half of what you would the first year, and then go in the next year and finish the job. This is good with a larger orchard, or on single trees where there is a lot of damage that you really need to prune very hard overall. You can also summer prune, or "French" prune as some call it.
Also over the years, I have become a very heavy pruner, especially on apples. Buy or have on hand a good set of Felco #2 pruners, a good set of loppers and a good small pruning saw. I bought a Felco folding saw that I really like last year on Ebay. Also clean up the pruning debris and burn it. Kill the disease and bugs before they can escape back into your trees.
