In this video tutorial I show, how to relatively quickly make a cartoon tree in Blender 2.73a.
My starting point is the following list of shortcuts, and otherwise require this tutorial is nothing more than the latest version of the free 3D program Blender from

Commands used:
X = delete
E = extrude (extend)
Z = see through things
S = scale (resize / make larger or smaller)
CTRL R = share things up in pieces
. (dot) = Provide precise targets
B = to select multiple points / things