Your lens cap will protect your camera’s lens and prevent it from getting scratched, dirty and damaged. It’s therefore essential you look after it and use it to fully protect your camera and its lens. Lenses can cost a lot of money, so it’s important you look after it and protect your investment. A lens cap that isn’t looked after can do more damage than not using one at all.
Make sure there is nothing on your lens cap, like dust and dirt. If you drop it, see whether you can clean it off and if not, purchase a new one. This is especially the case if you drop it into dust, sand or gravel. Squeeze it to see whether any of the debris has got inside and if it has, don’t put the cap onto your camera. Buy a new one as soon as you can, or you will end up transferring the dirt onto your lens.