They're supposed to be a little less difficult than an Achilles. I think the key is to get a healthy one from the start. These guys do not ship well. I was lucky when I got mine. He had ick for about a month and it disappeared never to come back.
Also a very healthy balanced diet. Everyday mine gets fed formula two flakes in the morning. At night he will get either frozen mysis, frozen formula two, prime reef or frozen formula one. Every other day during the day he gets a nori clip. On the days where he doesn't get a clip, he gets formula two pellets.