Marketing Experiments Journal has made a number of A/B tests on landing pages. They found that landing page performance can be improved by the following principles.
First off, what is a landing page? By this, we're not talking about a 'homepage' or main product page on your web site which people may randomly navigate to. Landing pages is a special term that refers to the pages people land on after clicking ads or search result link.
Designing a winning landing page should take the following points into consideration:
One Objective
Focus on one objective for each page and drive everything on the page to that single objective -- usually an button with a clear call to action such as an "Apply Now" button.
Vertical Flow with a Single Column
Use a vertical flow through the center of the page, usually with a single column:
Sales pages should use a vertical flow through the center of the page. For commercial offer pages, vertical single-column body copy through the center of the page consistently performs better than other layouts and should always be tested. Left or right columns should be used to support movement toward the objective such as testimonials (to reduce anxiety at clicking the Order button). Source
Eliminate Distractions
You should eliminate elements that may distract eye path from the flow toward the objective. This means you should remove page elements such as photos and graphic images that do not drive the user towards the page's call to action.
Use Eye-Catching Visuals
Use visual elements to draw attention toward the call to action. Visual elements can include size, motion, color, position, and shape.
Remove Off-Page Links
Avoid use of off-page links. Why?
Once visitors have left the page, their forward momentum is interrupted and must be re-established even if they do return.
How do you get around this?
Use passive pop-ups or launch new browser windows when needed to provide details or supplemental decision information. Source
Read more about landing page design techniques at Landing Page Confusion-How Does Having More Than One Objective to a Page Affect its Performance?