For this painting, I used a cartoony cross-hatch brush from Chris Wahl.
Step 1: Rough outline to locate main shapes. Since this painting was right out of my head, with no visual reference whatsoever, some things will change as I progress.
Step 2: Rough in undertones. Lighter and cooler in the distance, darker and warmer in the foreground. I adjusted the mountain shape so it would fully contain the main tree. I use a fairly large brush here to get the surface covered.
Step 3: Add weight to all tonal areas. I use some of the sky colour in the mountain colour. I do this by painting a transparent patch of the sky blue over the purple from Step 2. Then I select this colour with the eye dropper and apply it across the area. This helps to "absorb" the mountains into the atmosphere, especially the more-distant peaks.
I introduce highlights in the background and mid-tones in the foreground. I re-establish the main tree and distant trees and some minor detail is added to indicate a fence and track. I've also introduced a foreground shadow being cast from a tree off to the left somewhere. This small detail instantly adds depth - plus I like shadows falling across white sand tracks!
Step 4: Highlights are added to the foreground and middle distance. I've strengthened the track and foreground fence posts. By this stage, I'm adjusting the brush size up and down as I work on different areas.
Step 5: I decided to change the shape of the main tree as the earlier shape looked a little "weak". I've also marginally brightened the sky and added my digital signature.
(Imaginary landscape 2. 1500x1000px digital. © Andy Dolphin)
Step 6: Finally, I flattened the whole image, boosted the saturation a little and tweaked some minor details here and there across the whole painting. I could have adjusted the saturation with an adjustment layer instead of flattening - but I didn't.
There is a about 30-40 minutes work in this. Note that at 1500 pixels wide, this image would only produce a high quality (300dpi) print about 12cm wide! If I wanted to do anything serious with it, I could work at this size up to around Step 4 then increase the resolution before continuing with detailing.