Another easy test to try is button shape. You want there to be a high contrast between the rest of the page and your most important button or call to action, but there’s more ways to increase contrast than just color or weight. One way to make it stand out is by using a contrasting shape. How can you make this thing a true anomaly on the page?… Are all your buttons currently round? Try making your main button square. Are all your buttons currently square? Try making your main button round. If it sticks out as the one thing on the page that doesn’t belong, it will in theory attract attention.