Avinash Kaushik is the authority on website analytics and optimization. HNers are urged to devour the man's writings wherever they can get them. His book is a classic, and he is donating all the sales proceeds to charity :-)

I suppose, the question is, why do people which are not interested in what your site has to offer land on it in the first place?

This seems pretty obvious as an extension of "make something people want." Most people don't want to be at a site that doesn't meet their expectations.