Depends on what you're looking for. With African lit, it can break down by region. So especially with what you're looking for, the region will make all the difference. If you want to get into Kemetic shyt then the Metu Neter series is great and it's back in print for a limited time, Muata Ashby's books also fill in the leftover blanks of Kemetian mythology and practices. Science of the Dogon is good as anything involving the Dogon is good shyt. Kongo-Bantu cosmology will give you an introduction to the spiritual systems of the various Kongo-Bantu peoples.
I guess out of all books I'd start with Christianity Before Christ by John G. Jackson as it introduces you to all the different mythologies of outside groups that used the original stories from Ancient Kemet.