We suggest two caring products: Phoenix Handpan Oil, which was designed specifically for taking care of handpans and RAV drums, or Frog Lube CLP. If you don't have those available in your place, try using coconut oil.
Depending on humidity in your place, you should figure out how many times a month should you apply the product. If you live in a humid place, we suggest applying it once or twice a week. For the places with normal/low humidity it's okay to use it once or twice a month.