Like SD said, get any dead wood pruned out first. Also any limbs that cross over and rub on other limbs. The golden rule seems to be never cut more than 1/3 of the tree in a year with pruning time being in the winter Jan-Feb-early March. Cutting too much at one time will give you a tree full of suckers, that's the tall vertical growth that have few fruiting spurs on it. You want to get light and air into the exterior of the tree. I always walk around the tree looking at it from different angles before I cut a branch. It can be intimidating at first, pruning a tree, but you can probably find some good videos on You tube to help you.