This is something I did recently after I made a major discovery in photoshop. I used to change the opacity of my brushes when attempting to blend colors. The problem with lowering the opacity is that you have to make successively layered strokes, lifting the sylus off the tablet each time, in order to build the color back up to 100%. What I recently discovered is to not lower opacity but to lower the flow, all the while keeping the opacity at 100%. Using this technique I can now effortlessly blend colors in a much more naturalistic way. This is a major game changer for me. Did I say game changer? God, I'll be glad when this presidential race is over.