Building lasting and trusting relationship is really important in South African culture. The locals see relationship-building as a prerequisite before negotiating business deals.
Keep in mind the history of South Africa where the Afrikaners (whites of Dutch origin) and blacks used to co-exist in an unequal world. So be savvy when you are interacting with both races at the same meeting and do not touch on sensitive topics.
In general, high academic achievements, social status and corporate ranks are well-respected in their society.
The Afrikaners are more direct and blunt in their communication whereas the blacks are more subtle.
In terms of decision-making, South Africa is a hierarchical society and this process can take a longer time. Do not put unnecessary pressure on them or it could be a deal-breaker.