Your call to action can be several things. It can be an internal link to a related page on your site, a button or a form for to fill in or it can be a little read more button at the bottom of your post excerpts.

It is easy to build a call to action button with DaButton Factory and it is free. You can check it out at http://dabuttonfactory.com/
Build a button like this in seconds

If you want visitors to sign up for a newsletter or your latest post then build a sign-up form quickly and easily with the Contact Form 7 plugin. You have the option to collect as much or as little information as you want using this form.

This is the form I use. People are wary about putting too much information on forms like this so I keep it as simple as I can.

Keep your call to action simple and easy to find and use.