You can interview different teachers on your own, though many teachers are sales people as well, and can be very convincing that they are the best.
When I first moved to LA, I found myself some mentors, an agent, a working actress, and a casting director. I asked them which they felt were the top acting schools/teachers in LA. Based on their answer there were 4 schools that were on all three lists. I interviewed each and made my decision.
Choosing a good school/teacher is important to many casting directors when they look at your resume.
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