Not all colours are equal
Watercolours are either transparent, semi-transparent or opaque. With transparent colours, the white of paper will show underneath. With the opposite, the luminosity is diminished and layering becomes difficult. Another characteristic you’ll see is staining versus non-staining. With staining colours, the watercolour won’t readily be lifted after applied to the paper, which will make any stray marks a pain to deal with. Lightfastness determines how well the pigment stands up to sunlight and acids over time, so ratings of I and II are recommended. The properties of watercolour may seem intimidating; however, with practice, you’ll understand which properties in watercolour to look for when formulating a palette.