If you want to get into the personal coaching business but don’t want to (or cannot) hire someone who assists you in marketing, here is a bunch of books that I warmly recommend to anyone starting, or optimizing his business. (Assuming you’ve already read the authoritative works of your preferred coaching/therapy methodologies.)
Note that none of those books is really specific to the field of personal coaching, training or therapy. That is because, frankly, I haven’t yet found one that amazed me as those listed did. E-Mail me if you have a suggestion.