Step-by-step: creating a waterfall in photoshop
1 I start by blocking in the base colours and shapes of the scene at 100 per cent Opacity, using the Lasso tool to define the different zones of the painting, separating them on to their own layers. At this stage you should already be implying texture using brushes and bounce light.
2 I start the surrounding environment and use a heavy bristled brush with deep vertical strokes to add motion. Using a small Soft brush, I dab highlights along the length of the waterfall. I then blend these vertically using a textured Smudge tool to depict the body of the water.
3 I use a large, opaque chalk brush to suggest heavy spray along upper parts of the waterfall. I add an earthy bounce light to the water from the rocks and finally use a large soft Round brush (in Color Dodge mode) to create the billowing mist at the bottom of the fall.