I mostly used the line tool that fills in as you go to create the trees clouds and animals. For leaves, bushes and clouds I made a shape, then re-used it rather than making new ones every time.
I used the mesh tool a little bit...but I'm still not quite sure what difference it made...
But mostly I tried a little bit of everything in my piece, although I did delete a few things.
I then brought it to Photoshop and cropped it, then saved for the web.