Adding Adjustment layers
After setting the base colours, I usually change them using Adjustment layers. I mostly use Color Lookup, Selective Color, Brightness/Contrast, and Vibrance to make them more vivid and contrasted. I also change my Layer Blending modes with these Adjustment Layers by setting them to Hue, Lighten, Normal, Darker Color, and so on. This means I can selectively edit only the colours I want to edit. I want to bring out the complementary contrast by making the blues and oranges more vivid.