Africa is not a country, it is a continent. Comparing it to India or China (whose economies haven't really paid off for foreign investors as much as you'd think) is a major flaw. China and India have an incredibly consistent society from corner to corner and well organized governments. Africa on the other hand is a few dozen sovereign countries, without a common culture or language between them. They are constantly at war with each other and within each other.
I think in order to extract the full economic potential of Africa you'll need to see unification at levels that put the EU to shame and at least a decade of trusted, non-corrupt, forward looking governance.
I think it'll happen, but not for a very, very long time. Until then, follow the Chinese govt investments in Africa and try to tag along.