A call to action ("CTA") lets a user know what their next steps should be when visiting your webpage, typically in the form of a button or hyperlink. A CTA can be as simple as "Sign up today!" and is ultimately meant to help encourage a reduction in friction as a user moves through a website or sales funnel. Also, there can be multiple CTA's on a page when there are multiple desired actions to be taken.
The "right" way to make a CTA is the way your users will be encouraged to engage. Don't be afraid to test multiple options through techniques such as A/B testing, multiple versions of the same CTA on a page, running an ad campaign with varying language, and any other technique that best fits your goals.
Too many CTA's can cause fatigue, so funnel your users wisely. A helpful technique to practice is to assume a user is only going to be able to understand three deliverables on a webpage. With this in-mind, what are the three most important take-aways you can give? Is it a newsletter? A relevant product? Maybe another blog post within the same category? Whatever it may be, strategically place your CTAs to the users benefit or it will be ignored.