Snakes come out in the morning to sun themselves, most will move off before you even realise that they are there, but occasionally some (especially Puffadders) will remain still until you are very close. By midday they will have retreated under rocks etc. Don't stick you hands in to holes in the ground or move rocks around. Look at your feet when walking. Should you be bitten by a snake, keep the person still and calm, apply a pressure bandage (if you know how to do this) NOT A TOURNIQUET and send someone to get cell signal or to a landline (the latter is the better option for most of the Cederberg has no cell coverage) and call 021 937 0300, specific you have a mountain emergency, and you need a helicopter. In almost all cases it will be better to wait for the helicopter than to try and drive to a hospital.
Puffadder bites are the most common, their bite is cytotoxic (will cause localized damage) but will not kill you unless you get bitten over the heart or in the neck/head. Cobra bites are neurotoxic and will shut down your breathing and heart beat. Perform CPR and the victim will not die, after about 3-4 hours the poison will wear off. Hopefully you should be in hospital long before that though.