Simple Waterfall

Thin is what you want for this type of painting. The high-quality "Artist" grade paints are typically quite thick right out of the tube, and you end up thinning them with oil or turps to get the right consistency because they don't spread well when they're that thick. Watch those Bob Ross / William Alexander videos on YouTube, they're using a specially-formulated premium brand of expensive paint (Bob Ross had his own line that's still sold today) that's way softer than Winsor Newton or Grumbacher Artist-quality oil paints.