You could check out Warfare in Independent Africa by William Reno. It is quite recent (2011), and is published by Oxford University Press. The title is a bit misleading, as he does not really attempt to address interstate conflict on the continent, but he focuses on state vs rebel conflict. However, he does a very good job of looking at and categorizing various rebel movements, from Independence rebels, Majority Rule rebels (i.e. ZAPU-ZIPRA and ZANU-ZANLA, SWAPO and ANC's MK), Warlord rebels, Parochial rebels, etc. More focus is on political, social and economic factors than tactics and strategy (which sounds as it might not be what you are after)

In the same vein, there is also Understanding Civil War: Volume 1- Africa, Edited by Paul Collier and Nicholas Sambanis, from 2005. Again, this focuses not on tactics or strategy, but rather on arms shipments, local grievances, the resource curse, and the role of Cold War competition in the African experience.

A more focused treatment would be The Ethiopian Revolution: Warfare in the Horn of Africa which gets much more into the strategic thinking of the Derg government, the Somali government of Siad Barre, and the kaleidoscope of rebel groups fighting against the Derg and against each other. It is by Gebru Takere and was published in 2014.

If you are interested in the history of Sudan, you could read Scopas Sekwat Poggo's The First Sudanese Civil War: Africans, Arabs and Israelis in South Sudan, 1955-1972, which was written in 2011. Sekwat Poggo's parents were both involved in the Anyanya movement that fought for separation for Southern Sudan. He provides a very engaging and authoritative history of this period, drawing on much material that he was first to present to a Western audience.

For the most part, decolonization occurred without resorting to armed conflict for most African colonies. For instances of this, you would be looking to the case of Algeria (A Savage War for Peace is good) or Kenya (Imperial Gulag) or the Portuguese colonies. I have already mentioned Warfare In Independent Africa which discusses anti-colonial rebels in the Portuguese colonies. However, more specific reading about Hamilcar Cabral and his fight in Guinea/Cabo Verde would do you good (I don't have a book to recommend on this, offhand).

Similarly, if you search for more information about MPLA, FLA and UNITA, you will uncover information about their struggle against Portugese colonial government in Angola, as well as their post-independence power struggles. Ditto for FRELIMO and RENAMO in Mozambique. For a treatment that touches on the civil wars in Angola and Mozambique together, and South African involvement therein, I would recommend Apartheid's Contras by William Minter.