You have probably seen the case studies: "we changed the button from green to red and conversions went up 21%." These stories are usually real but misleading. The lift almost never comes from the specific color. It comes from the contrast change between the button and its surroundings.
What Is Actually Worth Testing
CTA contrast: Test a CTA color that matches your page palette vs. one that contrasts with it. This is the highest-impact color test you can run because it directly affects the most important action on the page.
Background lightness: Test a white background vs. a very light tinted background for content sections. This can affect perceived professionalism and reading comfort.
Trust section treatment: Test whether adding a subtle background tint to testimonial or guarantee sections increases their impact.
What Is NOT Worth Testing
Testing red vs. orange vs. green buttons in isolation is rarely conclusive because the effect depends on the surrounding colors, not the button color itself. Testing body text color variations (#1a1a2e vs. #333333) will not produce measurable results because the difference is imperceptible to most users.
Running a Valid Test
Change only one color element per test. Run until you have statistical significance (typically 1000+ conversions per variant). Control for time-of-week and traffic source. And most importantly: test the contrast relationship, not the specific hue.
Using PaletteRx for Test Variants
Build your control palette in PaletteRx. For the test variant, swap only the CTA color (or whatever single element you are testing) while keeping everything else identical. PaletteRx's contrast grid helps you ensure both variants are accessible.