Volcano Speedpaint

I have been working on a few attempts at speedpainting, and this is the first one that I am slightly satisfied with...

Please comment with tips on how I could improve it

Stats:
45 minutes
671x445 pixels
Photoshop Elements 3.0

I really want to improve, and it would help if you would leave a comment saying what I did good, what I messed up, and what I could do better. I would greatly appreciate it.

Happy Holidays!