Not at all happy with this one. :( Doesn't seem to have an interesting composition, bad values, etc. Last time I worked from a thumbnail and this time I was working from nothing, maybe that played a part.
I put the flip horizontal command on hotkey, which I found useful.
I also found it helpful in certain situations to set the brush mode to lighten or darken.
Blocked in basic composition from a small thumbnail drawing from my sketchbook.
Using the lasso tool, pulled in some textures of rocks from photos.
Selected areas of the image with wand and adjusted with levels to define planes.
In the middle of painting, took a break and looked at flickr images of fern trees, rocks and waterfalls. (The variations in nature make me feel so damn uncreative.)