Firstly – give diplomacy a full chance at working. (This wasn’t done… the US felt it was taking too long)
Secondly – get the UN backing
Thirdly – attack as a last resort only.
You know, under Apartheid you had two complete opposite sides in an evil national conflict. What happened is that two great men (De Klerk and Mandela) got together, then got both evil factions together and thrashed it out behind closed doors. A peaceful solution was found, and the New South Africa was born. The evil militant blacks and the white racist dictatorship was destroyed and the South African public as a whole was freed. Without war. Without bloodshed. Diplomacy.