I've been looking at leaves and using up my tubes of gold, crimson, yellow, pink, and siennas. I'll have to get a new stock in for the workshop! But it is great fun. As long as you get the outer shape of the leaf right, (and don't tell anyone, but a real leaf makes a wonderful template!), then you can go crazy with your colours and textures within the leaf.
In this painting I've introduced a bit of structure by putting in some branches and twigs. I like the dark, knobbly shapes of the twigs.