I'm going to take Charlie's school of thought one step further. When you look for an instructor, look for one you are compatible with. If you start taking instruction from someone you:
a) have a hard time understanding/communicating with
b) just don't like
c) have no chemistry with
you're not going to do well and may not stay in the hobby. Spend some time talking to the various instructors and find out who you can and can't work with. Don't be afraid to ask the hard questions like:
a) what kind of results have they had with other students
b) what kind of teaching style they use
c) are they willing to spend some extra time if you have something you're struggling with or will they cut off the lesson at the preset time.
Once you find one that you can work with, it's a team effort to get you to the point of being a proficient flyer. Be sure you do your part when it comes to learning because it's not just the instructors fault if things go badly. If you have something you don't get, ASK FOR MORE HELP!!!!!!!!!!!