Shading and Highlighting Fluids
Anyone, please add to this, correct me, whatever. I'm not an expert on the subject (far from it), these are just my observations.
One of the biggest mistakes people make when painting fluids is to shade the entire fluid as if it is a solid. The liquid itself, especially if it is semi-opaque, has a color gradient of its own. Use only these colors to shade, and do that as you would any 3D object with a light source. These colors can be very smooth gradients, don't worry about that, even if the "almost end" product looks very dull. For transparent fluids, clear or colored, the "other side" must be colored, and