Simple rule of thumb in most cases is if you can convert it to grayscale and still tell it apart your colorblind users can too. Barring that as a red-green col

Simple rule of thumb in most cases is if you can convert it to grayscale and still tell it apart your colorblind users can too. Barring that as a red-green colorblind person, yes red-green contrast is the worst, but way more common are colors that are only different by their red or green strength (especially red). The two most common by far being pink becomes white and purple becomes blue. Your green-yellow-blue suggestion is actually making the same mistake as red-purple-blue just using green as the fade instead of red. Having said that in my experience red-green colorblindness is actually RED-green colorblindness. So, I would much prefer a green-yellow-blue interface to a red-purple-blue one. As I am much more sensitive to green than red.