I have found doing quick black and white acrylic sketches is great. Very often I want to paint something but if I’m hanging out with people, I don’t want them to have to wait for hours. I think this is a great compromise,takes very little time and makes good opportunities for study. Also, it goes WAY faster than doing the shading with pencil as I was doing it before. I still prefer oil for its “buttery” quality, but this does the trick in terms of practicality, and I’ve started to really enjoy some dry brush effects.