Brush Techniques for Grass and Trees

To make smoother lines, add more paint (or thin out your paint with gel medium, to a syrupy consistency). To make rougher lines, use only a little paint, so it goes on unevenly. I like this technique for trees. Make sure you vary the angle you apply paint, so the trees don't all line up in exactly the same direction. By slightly modifying the angle and pressure, you can fill in detail very quickly.
To put the flowerheads on the grass, I used a variation of this technique with a fan brush:

When using the fan brush to add texture, I make sure to apply a mix of colors to the bristles, so the objects I'm painting don't look flat. You can do this by actually "painting" the bristles with globs of different colored paint before starting. Use another brush, or just dip your fan brush into some unevenly mixed paint on your palette to get a range of shades.
On the areas around the black labs' feet, I painted in the flowerheads carefully with a small detail brush. This detail has to be done precisely, because it is very visible and the eye is drawn to the contrast. For the rest of the field, the fan brush provides a more natural look of the overlapping grasses.
The grassy area is roughed in, but still not finished. I will use a tiny brush to put in shadows and highlights to tie it all together:


