One of the things Amazon does exceedingly well, and which works to your advantage as an associate, is track user browsing and buying behavior in order to make attractive suggestions.
This could hinder you when selecting products to promote. The products you see will be colored by what you have purchased or looked at in the past. Unless you are promoting to people just like you, you may not be seeing the best choices. And the more you search, the more skewed those choices may be simply due to extensive searching.
If you browse using FireFox 3.5 or later, you can use a feature called 'Private Browsing' to get around this. All you have to do is look under the 'Tools' menu, select 'Start private browsing' and click the button that pops up to start the private session.
Navigate to Amazon, and you'll see that it does not recognize you. Therefore, it does not have access to your buying and browsing history. You can search to your heart's content as if it were the first time you visited the site.
And when you end your private session, none of that search history will be saved, nor will Amazon have a cookie on your machine to reference that session or your profile.
As a side benefit, you also don't mess up the recommendations you get from Amazon for your personal use...