I have found it immensely helpful to make a watercolour chart. In theory the colours are mixed 50/50 but in reality this isn’t the case. Some pigments, such as phthalo green, are very overpowering. Therefore, I had to adjust accordingly. Also it’s amazing how just a touch more of either colour can totally affect the outcome of the final colour. So whilst the chart may not be hugely accurate it’s still a useful tool.
Painting the chart also proved to be a really great exercise too. For instance, I discovered that the Daniel Smith watercolours re- wet beautifully if they have dried in the palette. However, the couple of tubes of Artist Spectrum brand I had, were harder to re-wet. Painting the chart has helped hone my skills in mixing.
As time goes on and I become more experienced I won’t need to refer so much to the chart. However, in the meantime, it gives me a good starting point when selecting colours for a painting and also an approximate for when they mix and blend.