Great! It's getting better all the time.
If you want more variation with the trees set a dark and a light green of slightly different hues as forground/back color and go to brush settings, set the color dynamics to have 50-100% for/back jitter, 20% hue jitter and 10% for the rest. If you want more uniform, lower the values. That's how I did.

You could sharpen up the shores a bit too...