Animating z's in After FX

I have finished shooting in my booth but the animation process is not yet complete! I now need to animate the 'z' leaves that blow off of the tree.

Firstly I cut out Z shapes from book pages and scanned them into my computer and used photoshop to save them as PNG files.

I then imported them into After FX along with the film footage and animated five z's seperately. Once I had the position and timing mapped out I added rotation in aswell, making the z's sway as they blow in on the wind but spin manically when brushed away.