For my Elite Animation Academy online students I sometimes use the painting of Rob Ross to get the students to play with brushes and use quick and loose brushwork to block in a painting. Rob Ross is infamous for doing his half hour paintings live on TV and this low resolution painting was done in a similar time frame.
What is different from a traditional oil painting is that I incorporate layers for each element of the painting. For instance the main mountain is separate from the smaller mountain ranges in front of it and the foreground happy tree is separated from those as well.
One simple trick I show the students is to copy the mountain and flip it upside down wile making it a bit transparent and blurring it. I also used a smudge tool to hind at ripples in the water.
I don’t have the same soothing voice but my students are able to paint their own happy trees by the end of class.