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.
Make your button a different color
It’s easy and can often yield big results. Make it a color that really pops. The more contrast between the other page elements, the better. You want this thing to really stick out like a sore thumb. Be sure that your main call to action (CTA) or goal button stands out significantly more than all your other buttons or links on the page. If you’re limited to utilizing branded color schemes, choose the brightest color, opposite to whatever subtler color is used for the majority of other page elements. If you’re not limited in your color scheme options, I recommend using the free Adobe Kuler color picking tool to find a good complimentary color. Historically, orange is usually one of the best button colors, but you won’t know for sure until you test!