This is how I start.
Before painting a new work, I mix all the colors (an ample amount) and have them ready - this gives me the freedom to work over my painting, and not worry about the acrylic paint drying (because it’s hard to recreate same exact color). Also, having the palette in front of you ready to use (the main ones at least) makes it easier to work faster and smarter. This is for the people who know what they want to paint before painting it - and have an idea of the color scheme. Here are a few images of my skin tone preparation! Happy painting!!