Thanks so much for the info. I have some reading to do!
Hm, well, there are a couple specialized programs for it: Marq's Petscii editor seems to be the consensus favorite, but I personally use Petscii Cola. PJ's very own ptoing has put together this very neat primer for C64 stuff which has links to both at the bottom, as well as some examples of the various styles that Petscii can accomodate.
Unlike in mcol mode where you want to use a midtone (usually grey) as your background color, I'd estimate that 80% of Petscii pieces (including this one) use black as the background color, and most of the remainder probably use white. There are exceptions though. This piece of mine uses light yellow; this piece uses dark blue. This piece by Electric uses the red midtone and looks a little funky as a result.
Great piece. PETSCII art is great where is the best place to look to start learning more about it?
Good tribute.