There are two basic methods to tree pruning, and the type of tree you are working with will determine which method you should use.
The purpose of Central Leader Training is to reduce co-dominate stems, which when the tree is mature, can cause a split right down the trunk. With most shade trees, starting from the day you plant them, you want to inspect the tree and properly prune out any double, or competing, central leaders that will cause future issues. It is recommended to prune double leaders until the tree is 25% of its total mature height. This normally means you should prune the new tree every winter, for the first 5-7 years of the tree’s life. Maples and oaks are examples of trees that benefit from this practice.