Never have a picture of a well-adjusted African on the cover of your book, or in it, unless that African has won the Nobel Prize. An AK-47, prominent ribs, naked breasts: use these. If you must include an African, make sure you get one in Masai or Zulu or Dogon dress.
In your text, treat Africa as if it were one country. It is hot and dusty with rolling grasslands and huge herds of animals and tall, thin people who are starving. Or it is hot and steamy with very short people who eat primates. Don’t get bogged down with precise descriptions. Africa is big: fifty-four countries, 900 million people who are too busy starving and dying and warring and emigrating to read your book. The continent is full of deserts, jungles, highlands, savannahs and many other things, but your reader doesn’t care about all that, so keep your descriptions romantic and evocative and unparticular.
When your main character is in a desert or jungle living with indigenous peoples (anybody short) it is okay to mention that Africa has been severely depopulated by Aids and War (use caps).You’ll also need a nightclub called Tropicana, where mercenaries, evil nouveau riche Africans and prostitutes and guerrillas and expats hang out.
Always end your book with Nelson Mandela saying something about rainbows or renaissances. Because you care.
For full advice go to: http://www.granta.com/Magazine/92/How-to-Write-about-Africa/Page-1