You could ask your colour-blind friends what they think of the colour scheme… because they see it differently, they sometimes have a fascinating new insight into the colours and layout. I had to change a design once because my partner pointed out that if you can't see the colour differences, the whole page looks pretty much the same. There was no other visual hierarchy.

I live with an extremely colourblind guy, and I now use him as an informal litmus test. I've had way too many designs over the years that he'd squint at and say, “Where's the link?” that I've gotten quite good at safe colours and combinations.