DIY for freelancers

I recently had a conversation with a self-publisher author about the publishing process -- I've probably mentioned before that I'm fairly certain that's the route I'm going to go with the novels I am currently working on, and I wanted to chat with someone who has been fairly successful at it themselves.  I got a lot of valuable information -- everything from tips on hiring editors and cover designers, to information on marketing tactics and what times of year you tend to get more sales.

A recurring theme in all of this, though, is what -- if anything -- I can do myself.