The leaves and shading is still pretty flat right now.
Here's Facet's rough diagram from around PX:
What you should get out of that is, think in perspective, use more guidelines/grids (wrapping around the tree).
When you choose a process you have to figure what it will do for the piece.
Does it make completion more efficient in the context of that piece, does it fit your skill level, etc.?
Ultimately process is result.
Using this as an example:
You're starting with this blank round silhouette (assuming the blob look was part of the art direction or you could get away with some wacky cool forms, Indigo's tree is the extreme of this).
But unless you're seriously skilled while making it up on the fly, it doesn't carry as much info about forms or perspective as using construction/guidelines does.
Using that might also help you figure out where the light hits.
