Play as much as you can to keep your instrument well tuned
Whenever you store it, never leave it in the case, its better put it on a shelf.
Play it in shady places
Clean it with 90% alcohol vol. and a soft cloth
Put a layer of Phoenix handpan oil at least 2 times a month
Never play it or leave it in direct sunlight
Never play it in the rain or in very humid places
When you move, always put it in a protective bag