This list of tips and hints for qualitative research is worth checking out, if you’re going to do (group) interviews. However, I found this one to be only partially true:
Listen well and react quickly – you should never feel when you listen to your tapes – oh how I wish I had probed this a little more.
Because on the other hand, you don’t want to feel the urge to shout at yourself: oh shut up, they were almost saying something really interesting and now you’re interrupting them again!, either. (Not that I ever feel that way when listening to my tapes, of course…)