To prune a tree limb correctly start by sawing the limb on the underside approximately 1/4″ away from the collar. The collar is the swelled area right next to the trunk. Move your saw blade about 1/4″ away from the taper.
Saw about 1/3 of the distance up throough the limb from the bottom. Remove the blade from the limb and start sawing down from the top of the limb.
Finish sawing from the top down. By starting on the underside you can prevent the weight of the limb from tearing the bark.
Caution: Large tree limbs can injure or kill you if handled improperly. You should consider hiring a proffessional for large tree pruning jobs.