I've had fairly good success with my books on math and physics. It's not a living yet, but definitely helps with the bills. Amazon (via CreateSpace) is by far my best channel, though when I can bring traffic to the book's website I have decent conversions too. The mailing list works great, though I'm hesitant to milk it as I don't want to spam my readers.
To reiterate patio11's comments, make sure you run the business (80% marketing + 20% pushing the book to distribution channels), as this will give you very interesting margins, like 45% of the list price. In comparison, if you were to write for an established publishing company, you'll get < 5% of list price, so totally not worth it (unless you think they have a magical marketing department that can sell 10x more product than you could on your own).
I totally recommend it as a career option, though keep in mind writing a quality book takes a lot of time, like a year per book... Feel free to email me if you need further advice (or a LaTeX template). Be sure to also check out https://github.com/softcover/softcover Michael Hartl's kick-ass ePub/mobi production toolchain.
To reiterate patio11's comments, make sure you run the business (80% marketing + 20% pushing the book to distribution channels), as this will give you very interesting margins, like 45% of the list price. In comparison, if you were to write for an established publishing company, you'll get < 5% of list price, so totally not worth it (unless you think they have a magical marketing department that can sell 10x more product than you could on your own).
I totally recommend it as a career option, though keep in mind writing a quality book takes a lot of time, like a year per book... Feel free to email me if you need further advice (or a LaTeX template). Be sure to also check out https://github.com/softcover/softcover Michael Hartl's kick-ass ePub/mobi production toolchain.