Haworthia cooperi have very delicate, succulent leaves. They need more sun than other Haworthias or they tend to die back with too much water or slowly die with too little. Anywhere you plant them, don't water too much, because once the rot starts it will spread rapidly.
Haworthia cooperi will rapidly put out lots of pups and tend to crowd out other Haworthia. Their soft leaves and stemmy pups just kind of creep over everything. Once you get them established and healthy looking, they are very self-sufficient and can be left alone. I plant them in loose, well-drained potting mix and don't feed them very much or at all. They don't care.
Haworthia cooperi roots will die back in the colder months. Eventually they will re-establish, but they are easy to clean up by hand, and then you can just put them back where they came from. Lots of flowers in the spring.