How can you tell when someone truly wants to help you learn the language?

[Mimori]

Hello all, as you tell from the title of this thread what my question is. I have been trying to learn Japanese for the past few months using books and CDs, also getting in touch with people who say they are willing to help, but after the first few lessons they stop. I don't know what happened; they said I was doing a good job. So can someone tell me what why?