Forming a palette is pretty challenging when faced with a wall full of watercolours. All the technical considerations – lightfastness, colour mixability… transparent or opaque? Staining or grainy? Each tube is $5 – $20, so making concise choices is important. I can’t afford to spend money on colours I won’t use frequently.
I bought a couple tubes at a time and tried them out… mixing them up with less or more water, watching how they mix and react with other paint. Every paint is a little different. If you are looking for paints that behave consistently, watercolours are not it. For watercolours, it seems like the trick is understanding the idiosyncracies of each paint, and then exploiting those variables to advantage.
The little sauce dishes from Chinatown keep each colour in its own container; I use flat plates for mixing. This is the colour wheel I have ended up with (barring the earth tones, indigo and black), and I feel that it is flexible enough to work with for a while. It ended up being a little heavy on the blues – that is my own colour bias showing – though one of the blues was a free gift with purchase.
So now I am homeschooling myself on watercolour technique… much more practice to come.