I had been asked for a tutorial about waterfalls, so here you go. As always, there are many things that could have been added.
Take care of the landscape beneath the waterfall, e.g. paint it first; many cliffs do not drop straight down but have jagged edges where rocks stick out, or the large fall is precedented by tiny falls and currents.
The steady mist allows lush vegetation, and there are even birds in South America that nest behind the water curtain.
As usual, looking at reference pictures will help you paint better, but be careful; many beautiful photos are taken so that the water looks very soft, like hair. That is not natural, waterfalls always look foamy.
See my other tutorials about water:
Water - waves [link]
Water - reflections [link]
Water - colour [link]
"Ranarh's tiny tips" is a collection of iddy-biddy tutorials, each containing small bites of advice anyone can chew, aimed at beginner's level artists. They are not software-dependent. If there's a problem you have, something you feel someone should finally explain, or are just curious what I have to say on a particular artistic issue, feel free to tell me.