There are several techniques that I have found that I adore. I like to see texture in my paintings. So if it looks flat, I will add sea salt to a painting and paint a light tone on top and then remove the salt. It give the most amazing effect. I have tried the rubber liquid that you paint on and then erase off when it dries. I never cared for it. It was not consistent. I just plan a light source and work around it. The best part about watercolor is if you use dark colors (like I did above) and you accidentally paint into your light source, you can use water while it is still wet and remove the paint. Water and paper towels are my best friend. And you keep the light source whole.
