As one starts to style a tree, let the tree tell you what to do rather than you imposing a preconceived plan for the tree. When choosing a tree for a bonsai, the most important feature is the shape of the lower trunk and the spread of roots from the trunk (the nebari) since these features cannot be easily changed.  The big branches and their movement should be on the bottom of the tree and smaller branches and their movement should be in the upper portion of the tree.  The apparent age of the tree is all important whereas the actual age of the tree does not matter.

You should have respect for your tree just as the tree should have respect for you.  The apex of the tree should slightly bow to you as a sign of respect and it does this by leaning toward you.