I'm always suspicious of answers where someone states that they make alot. I know it happens, and I know that most people at least make something for their writing.
But lets say I were successful, and I had a good idea of how to make money (not saying I do, because I don't); then people, as is their nature, would flock to that person and try to emulate them.
This can only breed more competition...making it harder to make money the more is introduced.
Ultimately the best SEO you can do is to write good content about things that don't really have a presence (little competition). Google will notice this, and those seeking it, will find it. A little bit of SEO Copy in support of these pages is a good idea, though I would recommend that you do this on a seperate account, as alot of SEO Copy on your main 'creative' account might give it a spammy feeling.