Imo, the priorities are: uMu/Ulu/Morocco/(Hun)/Nongoma/Nodwengo. Other cities get 1 worker max.
Improve tiles for max growth in all cities. One city could become an offshore trade route city--probably Nongoma because it's hammer poor and needs lots of health bldgs. Nongoma could use four fp farms by border expansion, if possible. Atlantis can be the other offshore trade route city.
When a city can grow 1pop per turn, then build workshops.
Thanks for the advice. I'll assign one worker to all cities in Africa, and more to the priorities you've mentioned. I hope development can speed up when I start airlifting our mainland workforce.