What are legitimate business opportunities worth pursuing?

A few friends are getting swept up by Primerica, Melalueca, and other MLM-type businesses. My gut says to stay away because they haven't had anything to show for it. The proof would be seeing their life change for the better, and I don't see it. So are there any business opportunities that are worth trying out?

What are the various business opportunities that for entrepeurs?

Currently, I am seeking various opportunities but I do not know which one suitable for myself. Since, I am in this predicatment how would I know which form of business is worth getting involve in. In addition, what are the important apsects of starting a business, with very small amount or no money at all. This may sound very stupid, but is it possible to start a business with no money?

Are there any legitimate business opportunities out there that really work?

I'm interested in started my own business from home. What legitimate opportunities are out there? I'm not looking to be scammed. Please only respond with information that really works.