The key to pruning, with the wellbeing of plant and people in mind, is both perceptive and insightful observation. Identifying the orientation of a crabapple, for instance, and understanding the importance of a north facing leader; as the plants typical behavior would be to have the most prolific growth reaching for the south or south west. These types of broad view observations help us make choices not only relating to the trees wellbeing and longevity but also to the human plane. Often, we speak about the ease of the lawn mowers experience, keeping the mower happy often directly corresponds to the reduction in the hasty and impromptu removals of lower branches in the heat of the summer, not ideal for the trees health or attractive structure.
Much like being a good friend, listening is an important factor as well. Getting to know the natural habit of a particular species is the plants way of being our natural guide in letting us know how to best care for them. For instance, a forsythia is naturally a prolific caning plant, but will root out along its canes and ultimately starve its interior of beautiful blooms and young vigorous growth. Thusly, its natural habit will count against its longevity in its designated space as well as its most aesthetic feature.
Identifying when our pruning interventions are most supportive, for the plant and for the continuation of the relationship the plant has in its particular environment, is an important part of the process of ensuring a long and happy life.