I shrunk the picture to 150*150 to paint the back ground to make colouring the large areas fast. Then I expanded the picture to 440*360 to add some detail, then expanded to the full 716*680 to start work on the foreground.
I copied the entire (716*680) foreground onto the background and proceeded to use the undo brush to 'scrape' through to the background underneath. I started with the largest size of undo brush at full intensity and cleared the large spaces. I then used smaller subtler brushes to clean along the edges.
Shading the figure (1)
I worked out where the light sources were: white, high left (his left); purple, left hand; green, right hand; blue bottom right (his right).
On this basis I did some loose shading on the figure and added some green highlights on his sword arm.
Adding Reflections
Using air-brush and push-brush I created some reflections on the swamp bed distorted by ripples and tinted with occasional highlights.
The tree was blulked out according to the lighting scheme. I sprayed black down the middle and added purple highlights to the side.
These changes were reflected in the water.
Then I used an intense 1 pixel push-brush to bring out some crisp patterns on the sides of the tree and on the branches.
Shading the figure (2)
Now the other side of the cloak was highlighted using air-brush to apply colour and push-brush to crispen it up.
Adding the sword
This was quite complicated. I used the line tool to cut off areas (the two sides of the blade). Then filled them with the appropriate green. I then selected each green triangle using the wand tool and copied it to a new image. The new image was sprayed with 'shine' and reflections and then copied back into the selection it was taken from. This method gives a good crisp straight edge.
Misc
The grass was darkened and the submerged root was shaded.
Notice that there is a trade off between the dynamic activity of a sketch and the painfully laboured over richness of the painted version.
Apologies to the artist for changing his sword and adding silly swirly things.