Developing your site so that it enhances your visitors’ shopping experience and improves conversion rates does not automatically mean that you have a site that is friendly to the search engines. Similarly developing a site that is search engine friendly doesn’t automatically make it user-friendly. But these things are also not mutually exclusive. You can please both search engines and website visitors.
While search engines are important, keep in mind that your visitors are even more important. When making edits to your site always consider the implications on both your human visitors and the search engines as well. Every change you make will have either a positive, negative or neutral effect on your human visitors and the search engine spider. You need to know ahead of time the effect any particular change will have and use that as a basis for determining if its worthwhile or not.