+1 on learning yoga in small classes with an instructor who knows enough to see what direction your muscles and bones are going, and can help you make corrections. That can be someone with a 500 hour certification or someone who studied extensively in India.

I've done a class here and there, but just last week I started going to a studio and trying to develop a regular practice, and the difference between this instructor and what I've had in the past is night and day. Yes it's expensive, but that's because real instructor training is so expensive.