There are a lot of good videos available. Along with Arne Moe and Jimmy Blackmon, I’m impressed with Clay Hayes’ video on back tension.
Another series is extremely detailed, but aimed at Olympic style shooting... look up ArcheryWinchester on YouTube. While some aspects are different than the way we shoot, there is much knowledge to be gained that IS applicable.
As Terry Green has shown in his form clock article here, alignment, IMO, is the most critical concept we need to understand!
Good luck!