Hey man, it looks pretty good! You're definitely on the right track!

Here are some of the things I've noticed with your piece:

1. The leaf shapes look too similar, try mixing it up a little!
2. The shadows on the leaves are inconsistent with the shadow of the entire tree on the ground.
3. The shadow on the ground doesn't match the leaf shapes on the tree.

As far as a top down RPG, what camera angle are you going for? A LTTP top down or a BOF 4 -isometric-ish top down?

Just a couple things, but not bad my man!