The best advice I can give is have the tank nice and mature and plenty of stem type plants, they look particularly good swimming through thick plantings of Val. Almost like salt water fish swimming through kelp, especially when the Val has reached the surface of the tank and is forming a wispy floating canopy.
Get a good school of them, since they can be flighty ( long tanks are best for these guys) and a good group should help them feel settled. Also it is the best chance to see the males sparring and doing their displays to girls.
keep in mind they have tiny mouths, because of other species in my tank I also give my threadfins a feed of first bites at least once a week. And they need more algae based foods rather than protein rich, so if you can get vege flakes these will be good. Another good food for them but limit to once or twice a week is defrosted or live mosquito wrigglers, or if you can get them daphnia.
Adult cherry shrimp will be fine with these guys but the tiny newborn shrimplets will be fair game in the food department, which can be a good thing with regards to how quickly cherry shrimp can over populate a tank.
They will look nice on black sand, but as you can see in my pictures mine are all on white sand and they still, show amazing colour.
If possible for the best possible colour have the tank where it gets early morning sun, when the sun hits the tank the threadfins should go into breeding mode and their colours will shine.