How to use black and white to change the shade of gouache colours

There is quite a difference in how much black and white you need to adjust a colour. When making a colour lighter, it’s a good idea to start with pure white and gradually add colour until you get the desired shade. When darkening a colour with black, start with the colour you want and slowly add more black until you achieve the desired shade. It can be a good idea to experiment to find the right balance when adjusting your colours.