You need to be able to provide people what they want. In order to this you need to understand who they are, what they want, and put something in front of them (regularly) that can help them solve that problem. Again… building that “know, like, and trust” and you’re doing it without having to pay for ads constantly.
In fact, I heard a story recently of someone who sold a book on how to stop biting your finger nails (seriously) and they made quite a lot of money via email just showing their audience that he had a solution… so you can sell ANYTHING once you know who you’re talking to.
Most people get this part of the process wrong… and therefore have a tough time selling.