arylide yellow and another puddle of WN phthalo blue near it to mix my green. The other colors are WN Alizarin Crimson and WN Burnt Sienna for my red and rust.
I wet the surface of my leaf sketch with water and paint it with my lightest color--in my case it is green-- leaving some areas unpainted. Since leaves are varied in how their pigments change in the fall, I am only using the leaf I found as a reference for ideas and am not concerned with the final result looking exactly the same as the leaf.
Below I've added some dark spots (sepia mixed with burnt sienna) and some splatter. Have fun with it!
Fun with Fall Leaves serieswet-in-wet
The science of color in fall leaves