Arguably, just to leave them alone, neither exploiting nor trying to "help". It sucks and it hurts, but outside interference does not seem to help a society heal itself. This has been argued by more informed people than myself-- https://www.uvm.edu/~jashman/CDAE195_ESCI375/To%20Hell%20wit...
A local director of a gold mine here in Tanzania told me that all the profits of the mine go to the owners in China. I don't know how much profit they are making, but if Tanzania as a country does not benefit from the mines then the deal is better than it should be.
The ones that do it though are all religious institutions so their goals are more social/moral rather than economic or geopolitical.