How to Choose and Plant a Tree
The Vermont Urban & Community Forestry Program has published several great resources on choosing a site and planting a tree. These are available as pdf documents. Here are a few of them.
Protecting the Investment (10 Steps to Successful Tree Planting)
Or visit The Vermont Urban & Community Forestry website page on tree planting.
Another resource by the University of Colorado Extension Service with great photos and illustrations on how to plant a tree:
The Science of Planting a Tree