Keetmanshoop is a town in central Namibia which is famous for it's good-for-value car mechanics. Don't expect much else there. Although it is a good place to stock up on food for some gravel-road hitchhiking.
The B1 goes around the centre of the town so if you're going to the center you may have to walk a kilometer or two unless your ride takes you to the center.
From the Central Park follow the big Sam Nujama road (M98) towards the point where it merges with the ring road and you will find a good spot right in front of the 500-kilometers to Windhoek-sign. You can try to flag down cars as you walk but a small proportion of the cars are heading for the B1 so it requires some luck.
Towards South Africa
To go towards South Africa you should head to the new Chinese-built roundabout which is located approximately 2–3 kilometres from the centre of town. Follow the 5th avenue until it merges with the B1. If you cant find it you can ask for Canyon Hotel which is located halfway. When you reach the B1 you'll see the roundabout. South Africa is marked as R.S.A on the signs.
Follow the directions for South Africa but just go the Luderitz exit instead of the R.S.A exit. There is not many things on the road so you're very likely to get a direct ride. Although the scarcity of traffic means it could take a little time to get there.