Using the NS Novelties Cosmo Harness is a breeze. Just put it on like a regular chest harness and adjust the straps to your comfort. Make sure to pull the straps tight enough for a snug fit but not so tight that it's uncomfortable. When it comes to maintenance, since it's made of vinyl, you can simply wipe it clean with a damp cloth after each use. Store it in a cool, dry place to keep it in good condition. Also, be careful not to expose it to sharp objects that could scratch or tear the vinyl. Enjoy your stylish and comfortable Cosmo harness!