In a continent with over a thousand languages, one cannot ascertain that the African language one chooses to learn will also be the language one will need in her/his future dealings with Africa. Student interests, needs, and background (whether heritage or not) are multifarious and can neither be anticipated, controlled, or planned. Besides choosing a language, the learner of sub-Sahara has to overcome, with great difficulty, many bottlenecks in order to successfully learn. Learners of unwritten/under-described languages must think and operate well beyond the methodologies and organization of the better-resourced students.
Is there a formula for developing a knack for learning languages absent traditional instructor/textbook/tapes etc.?