How many projects do you work on at a time? How do you determine which project is next?

It depends. For editing, I will generally work on one project at a time, though I might do smaller assignments (blurbs, advertising copy, etc.) during the same time frame. Oops Detection and proofreading are handled, for the most part, by my assistants, so those services run on separate schedules.

As for how I determine what project is next—projects are scheduled based on how long I think they'll take. I usually have projects booked up in advance, and I work on them as deadlines dictate.