There are a lot of little ways to tweek osCommerce to work better. Many of these tips are very easy to implement as well.
One of the best ways to improve your osCommerce site is to view what others have done. The live shops section at osCommerce has a fairly extensive list of osCommerce based sites that you can review. Decide what you like and don't like about their site and implement those changes in your site.
Remeber, your store is an ever evolving creature that will never be finished. Continue to evaluate your site and others to determine what you can do to improve it.
One of the best ways to improve your osCommerce site is to view what others have done. The live shops section at osCommerce has a fairly extensive list of osCommerce based sites that you can review. Decide what you like and don't like about their site and implement those changes in your site.
Remeber, your store is an ever evolving creature that will never be finished. Continue to evaluate your site and others to determine what you can do to improve it.