1. The button should be of a reasonable size, larger than any of the other navigation buttons or links on the page. A large button has a greater impact.
2. Use a unique font to the rest of your website so that the users eyes are drawn to clicking this “call to action”
3. Use contrasting colour to the rest of your site on the button; something brighter or darker than the rest of your site to help direct the users attention to this button.
4. Positioning of the button is very important. Place it just under some copy that describes the key benefits of your service or product or in an area where the users eye is drawn to based off the rest of the websites design.
Here I have included some links to some websites that have the sort of “call to action” buttons that I am talking about;
http://transmissionapps.com/ - The “Download Now” & “Buy Now” buttons
http://www.filesharehq.com/ - The “Sign Up for Free Trial” button
http://paramore.is/think/blog/ - The “Continue Reading” button on blog
Let me know if you have any other ideas on how to get more “call to action” from button methds that I may have missed..