Here are some key indicators to look for: 

Branches – Living branches are easy to bend. If the branches snap, they are dead. 

Leaf Color – The leaf color should match the season it is in. 

Insects – Check for visible insects on the tree. 

Bare Patches – For Evergeen trees, look for sections of the tree without leaves year round. Some causes of bare patches are: animals eating leaves, pesticide damage, nutrients and water not reaching the branches