First advice carry alot of cash although not on you, this is africa mate. In my experience and from what ive seen having a Cv in hand usually works best, make your face known.
The first major obstacle you always need to overcome is licencing so first stop should be the CAA of that particular country. Be nice and always smile or life will be hell.
Also try and make a stop through tanzania there is a shortage of experienced crew but by the time you come people might have moved up.
Persistance is key, dont give up no matter how bad it looks. Usually the chance happens and you have to be there ready to go. Timing is important. Try to arrive just before the beginning of the high season so all your conversions can be sorted out. Thats when movement is high amongst pilots.
Good luck. It is an adventure