selecting training classes
I've been going to firearms training classes since 1980.
Most years I've gone to one class. Some years I go to two or three, depending upon schedule and geographical location and my cash flow.
One criteria I have always used is, has the instructor published articles in gun magazines, or written a book, and does their point of view make sense?
Not all of the instructors I have trained with were widely published, but it is one thing that I look at.
Another option is to research on the various firearms related forums (The firing line, lightfighter, getoffthex, etc.) and read after action reports from class participants. AARs can alert you to classes you might want to attend and also tell you what to expect, what gear to bring and what skills to practice ahead of time.
You can only learn from experience if you pay attention!