Instead of adding butter to the foil packets, try olive oil, grapeseed oil, or vegetable oil.
Poking small holes into whole potatoes before grilling them is an important step, so don’t skip it. The holes allow steam to escape from inside of the potato and prevent it from exploding.
I find that I get the best results when I use russet potatoes for baking, because they develop such wonderfully fluffy insides during the cooking process. You could use any variety you like. Try red potatoes, Yukon gold, or even sweet potatoes.
When making foil packet potatoes, or any other foil packet meals, be careful not to overfill the piece of foil. You want to be able to seal the packet shut securely, so nothing falls out.
If you are including meat in your foil packs, check the internal temperature using a meat thermometer to ensure it meets food safety guidelines.
Keep leftovers refrigerated in an airtight container or covered with plastic wrap.