This leaf behind the bird has some of the darkest values. The first layer is a greyed yellow, the second one has the shadow green flowing into the first wet in wet.
Here I`ve brightened the green a bit:
The darkest values are put in here. Tint the veins to a dull yellow green:
If you compare this bud to the foreground bud in my previous post, you can see how far back into the picture this one looks. Its not only because these colors are paler but also because the highlights have been subdued. This differentiation in planes is necessary in order to give depth to the picture plane, that is the third dimension:
One half of this leaf has an yellow underwash, the other half is bent in another way to catch the light differently, it is bluish grey:
Here I`ve wet the leaf leaving the lines for the veins dry. Don`t worry if some of them merge a bit, they will look more natural that way. Then I dropped in a green mix at the corners of each segment. They make beautiful shapes on their own which look very natural and unforced, the beauty of watercolors!
Drop in darker mixes in the same way and tint the veins. Paint the stem in yellow greens and pale pinks.
I`ve done these leaves in a different way. I had painted the entire leaf that is at the corner without leaving the whites for the veins. This is a watercolor technique that is not used so much. The lighter valued yellow veins have been painted on a damp wash. Usually while a wash is damp, it is at a delicate stage where you would not want to mess around too much, since that would cause streaks and `cauliflowers` in an otherwise smooth wash. But it is a perfect stage where you can paint in details like veins or other growths with a stronger mixture (that is less water on the brush than on the paper) to get darker valued elements in the leaf. You can get lighter values like the yellow veins in this leaf if you take a watery mix (more water on the brush than on the paper) and stroke the veins in carefully on a damp wash. The water pushes away the darker color on the wash giving lighter colored veins. Experiment a little with the amount of water you are using. This method is useful for details which need not be too prominent. I`ve also put in the yellow spots this way. On the leaf to the right, the spots are in colored pencil. The effect looks quite different on both the leaves: