My best advice for fruit trees is to try your best to discourage suckers and water sprouts from taking over and shading productive branches.

Prune in Summer the useless whips, and new buds will form in better locations. It is the short side spurs you want to encourage. Be careful not to prune heavy in Winter or Spring, because it encourages more non-fruiting shoots to quickly replace whatever was removed.

Winter wood actually heals poorly. Pruning along the diagonal to let rain slide off is a false myth that doesn't help, so instead always make the least wide cut wound possible. Never cut off the branch collar.

Old apple trees sometimes need supports added. Watch out for a leaning trunk or sagging branches holding too many fruits. A piece of lumber or a guy wire can really help a tree stay in shape.