How did you learn the IPA?

Question speaks for itself. I've been trying to learn IPA for the past three months yet I can't differentiate between certain letters, such as m (voiced bilabial nasal) and ɱ (voiced labiodental nasal). Do I need to learn the organs, for lack of better term, of the mouth too? I'm trying for a tutor-less approach but I'm starting to doubt I'll get far without it.