This excellent video describes how to use the 3-cut method for pruning, and why that method is so important.  The video runs about 10-1/2 min. total.  During the first 5 min., John from Land Designs Unlimited talks about the damage that poor pruning can cause, and how the 3-cut method prevents that damage.  Your aim is to leave a “wound” that the tree can easily and quickly heal.  At about 5 min. 15 sec., he discusses the correct tool to use when you prune:  a pruning saw (there are several in the shed), NOT a handsaw or lopping shears.  During the last 4 min., he demonstrates the 3-cut method, and includes a couple of extra tips.  This video is well worth your time!