How did you begin to develop a base of competent beta readers who weren't friends or family?
This is a tricky thing, isn't it. I started off at Critters and the Online Writing Workshop, which both introduced me to other writers who were looking for readers to help them out, and I struck up a few friendships that way.
It can be difficult not only to find readers who get what you're doing and are willing and able to help you do what you're aiming at, only better, but also to figure out how to sort through the information they give you. In my opinion, that's one of the ways that giving critiques yourself can be even more valuable than getting them. So it wasn't just the folks I began to make connections with at those critique sites, but also the critiquing I was doing for everyone else that helped me in that process.