What has worked for you to find advanced readers?

[Raven,]

From what I have heard, it is easier to get readers after publishing than to get advanced readers, let alone reviews from them. Yet, books with no reviews are harder to sell. How many advanced readers have you gotten from here, and what avenues did you use? Since I’m nearing the release of a series of self-help workbooks, and finding advanced readers will be my next step, I’d love to hear everyone's advice or warnings.