Your CTA must attract attention, and the proper use of color can help to accomplish this.

You want to select contrasting colors while still ensuring the CTA looks great on your page. In addition, some colors can inspire certain emotions.

For example, the best performing colors are green, which inspires growth, and orange, which is associated with confidence.

The size and shape of your CTA button can be a tricky matter.

You want the button to be large enough for the user to spot easily, but not so overpowering that it appears sales-y or takes away from the meat of your content.

Play around with different shapes, sizes and graphics until you find one that works well on your page.

CTAs should be short and to the point.

Marketing experts recommend just two to five words, so it’s important to make every word count. Always start with an action word, like "try," "download" or "open."

Studies also suggest that using first-person language can increase your click-through rate (CTR) by as much as 90%. For example, instead of saying "Download your free e-book," say "Download my free e-book."

The placement of your CTAs must be purposeful and strategic.

When creating a long landing page, one CTA always should go before the fold. But, don't be afraid to include multiple CTAs that visitors can see as they scroll.

The user should never have to backtrack up the page to find a CTA.

81% of Americans now have smartphones, so it’s imperative to optimize your CTAs for mobile phones. Specifically, it's important to make sure any pop-ups on your website are user-friendly.

Google announced that it will punish sites with intrusive pop-ups that make content less accessible on mobile devices.

Make sure your pop-ups don't take up the entire screen so users can choose to opt-out easily.

Consumers are always looking for great deals.

Using value proposition language, like "free," "50 percent off" and "discount" can help the consumer see the value in what you are offering.

You also want to encourage the user to act quickly. Words like "now," "today" or "for a limited time" can help create a sense of urgency.

It’s crucial to test the effectiveness of your CTAs on a regular basis.

A/b testing, with the help of Google Analytics, allows you to test variations of your CTAs to see which one performs better.

This type of testing can help you perfect your call to action and improve your click-through rate.