Give parsley a try. That's what I use for my leaves. Other dried hurbs will work too.
In The Fall that's what I did.
http://www.armorama.com/photos/showgallery.php?cat=12095&ppuser=242I made the trees and I mixed terpentine and oil paints to mix and match fall colors. I painted each leaf and put up to three coats on some. One yellow based, one red based, one brown. Some of the shades were a touch on the brown side.
You can even use hobby paints like Apple Barrel or the like. I think the color scheme depends on the tree and area. I went with a yellow/red/orange scheme. You can go with what you like. I used Yellow, Red, Burnt Umber, Black, White and mixed and matched.