The importance of good quality, well-fitting hunting socks cannot be over-emphasized for an Africa safari.
It is advisable to bring a selection of socks of different thickness. It is not unknown for feet to swell in the heat, making your footwear tighter than normal and a thick sock will compound the problem, which can lead to blisters. You may want to try wearing 2 pairs of thin socks over each other to reduce friction.
A worn-out sock with thin areas and holes are very likely to produce blisters.
Do not wear untested or brand new, unwashed socks.
When walking long distances, it is always a good idea to carry a spare pair. Change them regularly if your feet become sweaty or wet. A good tip is to dust your feet with talcum powder before you put on a clean, dry pair.