5. Sketch with Old Holland Warm Grey
The warm grey from Old Holland paints is the perfect nothing-something color for sketching everything, since it blends wonderfully behind skin tones, still lifes, and even bolder fun colors. The final blend lines can be mooshed (technical term) beautifully and look rich and purposeful. Other greys exist, some cooler, some pinker, but I find that this particular warm grey is absolutely the best. Dilute it with Gamsol or turpentine to get just the right consistency for your under-drawings, and don't worry about pencil marks or unmarried colors.