Here are tips on how not to kill a tree

Mechanical damage and improper care kill more trees than any insect or disease. Few residential trees die of old age. Multiple mistakes could lead to stress of a tree and possible death.
Here are some tips on how not to kill a tree:
•Do not top trees. Tree heights can be lowered by proper crown reduction that does not stimulate water sprout production. Cutting a tree too severely only promotes entry for diseases and insects.
•When a tree is young, select one of the competing upright branches to be the main central leader and cut the other off. Co-dominant leaders can split during wind and storms.
•Remove branches that cross and rub in order to prevent bark wounds.
•Monitor for insects and diseases and treat appropriately if they are found.
•Do not use anything to cover pruning cuts or wounds - trees seal their own wounds.
•Cut broken branches off at the branch bark collar.
•Spray the lawn with herbicides that will not damage trees.
•Mulch around the tree to avoid hitting the tree trunk with lawn or edging equipment and to protect surface roots.
•Know how big a tree will grow (mature height and width) and space accordingly away from houses and other obstacles.
•Do not make flush cuts. Cut on the outside of the branch bark collar. A flesh cut leaves a large surface area to heal.
•Stakes generally are not needed on small residential trees, but if they are, remove them after one year to avoid damage.
•Do not wrap the trunk with anything except a wide wire cage if animals are a problem.
•Do not put mulch in contact with the trunk. Pile mulch only 2 to 3 inches over the roots.
•Do not put any fabric or plastic material under your mulch.
•Do not stack items on top of the roots, this causes soil compaction.
•Take the roping off of balled and burlapped trees and from around trunks. Pull burlap off of the top of the tree and pull down several inches. It is not necessary to remove the burlap.
•Divert water from the roots of trees that do not like wet soil. When you do water, water deeply to encourage new deep root growth.
•Dig the hole at least twice as wide as the root system to encourage lateral root growth out of the root ball. Do not amend backfill for individual tree holes. Only amend if the entire planting area can be equally amended.
•Dig your hole only as deep as the root system and do not put gravel in the bottom of the planting hole unless you install a drain to actively pull extra water away.
•Stress symptoms caused by tree root damage may take up to five or ten years to fully develop. Older trees do not adapt well to changes in the environment.