Place items in your pockets that are closest to the inside of the roller coaster. Only do this on a roller
coaster that doesn't go upside down.
Wear clothing with pockets that either zip or button. Having zippered pockets will secure your items more than pockets that have buttons on them.
Place smaller items into the closed pouch in front of you, attached to the roller coaster. These are designed to keep your items from falling out during the ride. However, some rides won't have these.
Wrap straps of a zipped backpack or zippered purse around your thigh, past your knee and keep your foot on the bottom of the coaster. To keep it more secure, wrap your backpack around the leg that's closest to the inside of the roller coaster. If you're on a coaster with no bottom, this will not be possible.
Leave items in a locker that may be rented at the amusement park. Some places will allow you to put personal belongings in set-aside areas that are next to the ride, so you can pick items up after you get off the roller coaster.
Give your items to a person in your party who isn't going on the roller coaster.