If you're an oil painter - you owe it to yourself to watch this demo.

https://www.youtube.com/watch?v=HqyXxUBmaNg You might find the remarks and background natter from the class before which this is filmed slightly irritating at times - there's a diversion into whether Sponge Bob Squarepants is worth watching or not, which you'll probably be happy to do without - and you might not even like the painting, although I do: but there's a wealth of information to be gained along the way, from mixing "mud", to the necessity or otherwise of the focal point, to reclaiming paint sludge at the bottom of your tin of spirits, even; and the limited palette. For anyone who thinks there are rules in painting - beyond perhaps the very obvious ones designed to keep your paint on the canvas - which must be rigidly observed, or clichés which are generally true: watch, and gain another perspective. I found this one of the most interesting demos I've yet watched.