Actually you've brought up the next challenge of an artist, which marks to make! Look at the paintings of David Hockney (or even his iPad doodles), there's not

Actually you've brought up the next challenge of an artist, which marks to make! Look at the paintings of David Hockney (or even his iPad doodles), there's not a straight line or neat circle in sight. But he's a relentless doodler. As Hockney says himself, art is just seeing. The more you practice, the more you see, the better you are at knowing which marks to make. I'd recommend this doc if you're interested https://www.youtube.com/watch?v=Cdqch3-D94A https://www.youtube.com/watch?v=Cdqch3-D94A