Staking and tying off a leaning tree is a fairly common practice, but it can be avoided by properly planting the tree in the first place. Often times trees lean because of limited access to sunshine. If a tree is planted in the shade of another tree or structure, it will grow toward the available light. As limbs grow predominately on the sun side of the tree it will also become heavy on that side adding pressure to lean that way. Before planting, look at the shade canopy of surrounding trees and try to stay outside them. This way you can avoid staking out your new tree as it grows.