Compare the two buttons, calls to action, for the same free eBook:
[By the way, you can get that free eBook by clicking either button]

        OR       

Do you see the difference? Do you know that this difference has a huge impact?

Here's another example:

        OR       

It's not about how many words I use in either one. It's all about the value for your visitors.

What do they get in exchange for the click?

Click is a very important action. Every action you ask someone to take implies value offer/proposition. Your visitors have to get a feeling that they get something in exchange for the click.

First calls to action in each set, "Click Here" and "Register Now," require visitors to do another action in addition to the "click" itself. How does that benefit them? What value do they get?

On the contrary, "Get Your Free eBook" and "Reserve Your Spot" benefit your visitors in the exchange for the click. Yes, they still have to click that button, but it's a fair exchange now. They will feel benefited and satisfied while clicking that button.

What does that mean to you? Better conversion rate.

Conversion rate = percent of visitors that take desired action (click, buy, register,…)

So, every time you're asking someone to take an action be sure to "give" them something in exchange.