Optimizing for conversions and optimizing for organic search results have seperate goals and seperate strategies. A landing page is a stripped down web page with a conversion goal. This goal could be a purchase or a lead in a lead generation campaign. Multivariate testing is a way to test page elements (like copy and graphics) and get feedback on how those elements effect conversion rates and ultimately ROI. Google Website Optimizer is a freely available multivariate testing tool from Google.
The best contacts and resources to help you get it done
Decide Which Elements to Test
Before testing you need to identify your goals. The first step is to define your conversion. What is the call to action of your landing page? What page defines your conversion (such as a "thank you page")?
Once you've identified a landing page and a conversion page you need to decide which elements you are going to test. Good candidates include titles, graphics, forms, and the call to action button.
I recommend: For additional ideas about what to test see GrokDotComs
64 Tips for Getting Started with Google Website Optimizer. Another good resource is Conversion Rate Squirrel's
101 Easy Ways to Use Google's Website Optimizer.
Setup a Multivariate Test with Google Website Optimizer
Once you've identified your test and conversion page and the elements you want to test, you are ready to set up an experiment with the Google Website Optimizer.
Using the tool is fairly simple, but does require the ability to edit the html code for the test and conversion pages. You will need to be able to insert javascript tags into these pages.
In order to use Google Website Optimizer, you need to sign up for an AdWords account if you don't already have one. Once you have and account set up, you will have access to the tool.
I recommend: See Google's
Website Optimizer page for details of signing up for GWO and for details on getting a test set up. I have also written an
introductory article on getting started with the process.