Branches should be well spaced and evenly distributed on all sides of the leader. When looking at trees in early spring, most deciduous trees will be dormant. Scraping the bark of a live branch with a fingernail should reveal green tissue beneath. If not, the branch may be dead. Check other branches to determine the status of the tree.
Live branches are quite flexible for most plant species.
A dead branch will snap and break. Buds, present since last summer, should be swollen and plump. The tree's previous growth can be checked by observing the bud scars on the branches. Check the trunk for mechanical injury, environmental injury such as sunscald, or animal damage. The top of the tree isn't the only area that needs checking prior to purchase.