Yellow is the lightest and most delicate of the three primaries , so if you're glazing ( building up colour one layer at a time) you should always start with your yellow, otherwise it will be overpowered by red or blue. Yellow watercolour also tends to lose its transparency when used over the top of other pigments, so to keep that beautiful luminous look it needs to be first on the paper.It gives a beautiful warmth to your work if used as an underpainting.
The four yellows which I use , from left to right, are:
Aureolin - a lovely cool transparent colour , makes lively greens
Cadmium yellow medium- an opaque yellow
Raw Umber- the one I most often use for NZ bush (see the last blog )
Raw Sienna - a beautiful delicate colour, great for underpainting and unifying your painting.
There are lots of others - different cadmiums, Indian Yellow, Naples Yellow ,Lemon Yellow- so try them out and find which ones will help you add warmth and light to your work.
PS. remember that many paint pigments, especially cadmiums , are toxic - don't lick your brush!