How to Blend Paint
This is a quick demonstration of my color blending method, and how you can use it to mix shades if you're learning how to paint. Beginners have a tendency to overmix their paint and work from too many pre-mixed shades, resulting in flat colors and paint-by-number looking paintings. This is my technique for making a wide variety of shades very quickly as you work.
To start, put dabs of paint on your palette a few centimeters apart. Try to distribute the paint so that the colors you'll be mixing will be close to each other, but don't overthink it. Some artists use a circular arrangement of paint on the palette. I tend to just make a few groups of colors with some space in between. For the demo, I'm just using two colors, yellow and green.
Begin by adding a little bit of water to your brush and pulling some color out of the side of the paint dab and onto the clean palette area next to it. I call this my "sidemix" but there's probably a proper word for it. Spread the paint around a bit so that you have some room to work. Next, without washing off your brush, do the same to the adjacent color so you have a thin gradient of paint that changes from the first color to the second color.
Now your palette is set up in such a way that you can select from a wide variety of shades within your sidemix each time you add paint to your brush. Once you have practice, you can make these mixes in a few seconds. Your original dab of paint stays fresh and untainted by other colors, since you're pulling color out of the side.
If you're new to this technique, you might be wondering what to do if you are painting a large area and run out of the shade you selected, since you only mix a little wee bit at a time. The answer: you will have to mix it again. And again, and again, and again, taking paint out of the side of your paint dab. The constant remixing is the heart of this technique - you are continually customizing your mix as you go, resulting in a wide variety of closely related shades that together will make the objects you paint look more luminous and three-dimensional.
A second trick I've learned to tie all my color mixes together is to avoid rinsing my brush off during painting sessions. Unless I'm going from black to white or switching paintings, I usually just wipe my brush off on my painting apron or on a rag. This leaves traces of paint on my brush, which go into my sidemix as I select my next shade. It's important, of course, to clean your brush thoroughly when you're done painting for the day - but unlike you were taught in kindergarten, you don't always have to wash your brush between colors.
By the end, your palette will look like this:
When you run out of space for making sidemixes, it's time to get a clean palette.