Welcome.
1. Stay away from the Transvaal side of the dam. I've never caught anything there except mosquitos, a tan and one 15cm carp.
2. Go in at sandveld. Drive through the caravan camping section. There is a fence that runs down to the water on ur right if u come out between the trees. Fish about 400m to the left of the fence if u are looking at the water. This spot is very good if the dam is empty. There is a very deep hole there in comparison to the rest of the stretch of "beach" when the dam is empty.
3. Another good spot is to drive from there away from the fence for quite a distance and the dam curves to the left. Around the bend there is a lone Acacia tree. In front of here also very good, best carp catches regarding size were made here, but u have to cast far, or take the bait out.
Regarding bait:
Carp - Groundbait, cooked chick-chick no 2, with about 1/2 cup of sugar. Take care it doesnt burn or use microwave.
Hookbaits, no1 is erdwurm, then and don't laugh, brown bread dough with liquidized onion kneed into it.
As dip, id take molasses powder, and any berry type dip.
For barbel, no 1 is a carp head lightly smashed with hammer. MAKE SURE UR HOOKS ARE BIG ENOUGH AND COMPLETELY PROUD. wait for the 3rd run then strike. Also very good is a dead mossie or vink.
If you plan on the river, any spot 3km or further down from the dam. Best bait here would be a young vink stolen from a nest, or flatties with carp head a very close 3rd.
Carp in the river, anything with cinamon.
If you have fished the dam, it's always worth it to take a few small carp heads and make a 6 hour session on ur last day at the river just for barbel with the carp heads.