I'm in a similar position. My situation is probably a bit different, however. I'm finding that managing the clients is easy compared to managing myself.
Short answer: I need some sort of structure to keep everything from swirling around and blending together in my head and bringing on that feeling of being overwhelmed. I also need some flexibility so that I can follow what feels "right" for me to work on in a given day.
Long answer: I'm very upfront with my clients explaining that my creativity and ability to work both wax and wane, but sometimes not in sych with each other. Therefore I cannot take jobs with large amounts of time-sensitive work, but ongoing maintenance usually isn't an issue. Second, I explain that existing clients come first. I'd rather turn away a new client than disappoint and anger an existing one.
I've had one potential client thank me and look elsewhere and I currently have one waiting in the queue because, "If that's how you treat existing clients, I'll wait and become one."
Like I said, easy.
Managing myself and the work, is another matter entirely. I'm ADD and a workaholic (among other things). I'm fortunate that one project is an intranet and once I'm off-site, I can't work on it. It's broad enough in scope that I don't get bored with it and I'm usually able to keep my focus on it.
The rest I try to set aside in day or half-day blocks. That helps keep me from getting bored on any given project and helps keep me from becoming obsessive about working. Helps is the key word. I blew all waking hours last weekend working on two pages of a single proposed design. I think I ate, I'm not sure. At this moment I'm putting off checking data on 74 pages of a directory. I'm bored before I start.
I guess the key for me is something to keep the pieces separate yet not so rigid I can't access them randomly. Hope this helps rather than confuses.
"the most incredible feats are often accomplished by
those who have had the most incredible challenges"