My biggest mistake was not going to the field to meet anyone. Our club has a website with all the contact info for instructors. I called the first one on the list and made an appointment. It turned out really bad and I had two crashed planes at the hand of that guy. One was a total loss including engine. I know this is probably very rare and not one of the most common mistakes new people make but anyway that was my experience and I think it would be wise to just go out to the field and ask people who a good instructor is. If I had done that, I would have had a smoother introduction to the hobby.