Here is a detailed instruction of how I paint a realistic tree. Although my style is not necessarily yours, it would be a good starting point.

The clusters of leaves that I talked about in the first part of this lesson, each get their own light. Some are mostly in full sun with only little shadowing below. Others are in full shade, and are painted with pretty much one color and one value. In between are leaf clusters with very interesting shadow patterns. I paint leaf shadows a very blue green rather than a darker green. Its a pretty advanced concept, but its covered in my lesson "Shadows In The Landscape".

Every tree has "sky holes". The are less likely to be in the middle where the tree is densest, but as we get to the edges there are those holes. The tree holes are more prominent in spring and fall, and less so in the summer, but a tree without holes is a lollipop.

A very important trick in painting a tree is connecting it to the ground. Just soften the edge of the base. That almost always is the touch you need. Finally, don't forget the shadow the tree casts on the ground. It too has "holes".

You want to take Part 1 before this one.