Simplify what you're wanting to paint by breaking up a tree into its components. Observe these individually, rather than as a whole, before you start painting.
- Taper the width of the trunk from bottom to top, as well as branches and twigs.
- For more character, paint trunks sideways in small strokes rather from top to bottom in one long stroke.
- Trees in dense woodland tend to be vertical; lone trees may be angled due to wind.
- Branches aren't straight, aren't the same width throughout, and don't grow parallel to each other.
- Avoid putting branches opposite each other on a tree trunk; trees aren't symmetrical unless they've been pruned that way.
- Make branches cross over each other to create depth. Add appropriate shadows.
- Leave gaps in the foliage and show branches in the gaps.
- It's insane to try to attempt to paint every leaf on a tree. Look at the leaves as a mass (or groups of color), not individuals.
- Trunks and branches aren't a simple, uniform brown. Study the bark of different trees up close not only for texture, but also for color, and make notes. Look at the color of new growth, old, and dead branches. For example, gum trees have silvery creams and oaks grays. Is there any moss or fungus growing on the bark?
- Trees in a woodland receding into the distance aren't all the same green. Aerial perspective applies and benefits from a bit of exaggeration.
- Look out for highlights reflecting the blue of the sky. Early morning sunshine will add a warm, golden glow.