1. Avoid colour picking, (no ALT) instead try to manually pick your colours using the sliders and your brain (know when to change hue,sat or value).2. Avoid additive blend modes, painters didnt have 'Screen' so they had to use opaque colour to indicate light, including glows.3. Use random colours but stick to the value. I put the painting in black and white and paint with the right value but choose a random colour and saturation.4. Use swatches. You can extract swatches from images, I extracted a bunch from master paintings and now have a nice random color swatch collection.5. Brushes DO matter (just a little). Some brushes will work better than others, try painterly/texture ones.6. Erasers are just as powerful as brushes. Cutting from a brush stroke often looks better than just the brush stroke. (I need to do that more)7. Use the magic wand. I make random selections and use vibrant colours to paint in them. Looks painterly, I guess....8. No opacity, paint everything at 100%