One of the most basic marketing concepts is also one of the most often overlooked, and that's the Call to Action. Every website should have a reason for existing, whether that's to buy now, register, learn more, sign up, contact us, or fill out a survey. It should be obvious what you want the viewer to do; for example, this marketing company wants you learn more.

On the flipside of not having a call to action are the sites with way too many. This confuses the viewer so they don't know what you really want them to do. Of course, most sites have many purposes. In this case, look at each page one screen at a time. The term Above the Fold refers to the space the viewer sees without scrolling down. There should be one strong call to action in this space. Then if you scroll down past that, you can include additional calls to action so that each screen's height contains one or more that are logically presented.

Take a look at the Las Vegas community guide. Above the fold, the main call to action is the free relocation guide and since this site is ad driven, the large ad also acts as a CTA. Scroll down a screen and you're presented with 3 bugs asking you to "explore". Scroll down past that to the bottom and there's an opportunity to promote yourself on ProSpotlight. 

If your page doesn't direct a person to the goal of your site, or if it's scatterbrained with too many calls to action, the user is going to leave the site frustrated and your conversion rates are going to be low. Make sure each page has one solid CTA. Move additional ones to other pages or lower down on your page so that the viewer sees them as they scroll down.