The real opportunities lie in the niches.

The optimal niche must be not too broad and not too narrow. Can a single person ever fill a Web site about, for example, "Marketing?" On the other hand, a Web site about "Internet marketing in Guinea-Bissau" will not attract many interested visitors. The right niche lies between these extreme examples.

Have in mind that the search engines are becoming theme based. This means that instead of only looking at the content of individual pages they look at the content of all the pages in the Web site.

So if you choose to develop a broad concept like "Marketing," with several major sub-themes, it will be harder to rank well for the sub-themes than if you dedicated a single site to a sub-theme. The simple recommendation is to keep your niche as narrow as possible, yet still with enough profit potential.

Concept

Try to look at the concept from the visitors end. Who are they? What do you want these visitors to get out of your Web site? You should have clear, concise answers to these questions.

Don't stop after discovering the first niche concept. Write down concepts as they hit you - make the list as long as you can. Just write down ideas for site concepts as they occur.
Take your time on this - the final concept will form the foundation for your future success.