I don't reply hardly, but since you're using my method I will.
First off, you need more transitions between the darker colors to the lighter colors, this way it appears more curved and it doesn't have such a dramatic shape to it which isn't realistic.
I never mentioned it but the only other tool I really use is the smudge tool, when combined with the layers that I use of the colors - for example: dark dark green on bottom, dark green in an area on top of that, to green on top of an area on that, to a light green on top of an area, then to a light green and then maybe a white depending on the texture I wish to create. That's how I would shade the greens on the areas you made, then I'd smudge them all together and maybe touch them up a little with the colors I'd used earlier. Don't up the hue so much next time between jumps in colors so much and also do more jumps. It's a nice attempt though for a first timer using this method. | 
