I was flipping through the online version of entrepreneur Bruce Judson's book Go It Alone! and came across an interesting concept: "relentless repeatability." In a nutshell, Judson beleives the ability to reduce your activities into a process you can refine and easily replicate is a key to success.
I think this is particularly relevant to performing artists. It's easy to spend too much time and energy on events that aren't repeatable (such as one big blowout gig that exhausts your fans' attention) while allowing the things that should be easily repeatable (such as lower-level booking and promotional tasks) fall through the cracks.
As I once wrote, once you start getting regular work as a musician, your calendar is always full. You can save your sanity by identifying the things that work, creating a game plan to keep doing those things more efficiently, and shedding the rest.