Choose a piece of jewelry that has a protective crystal (black tourmaline, garnet, amethyst, clear quartz, hematite, smoky quartz, black obsidian, shungite, selenite, labradrite, pyrite, or tiger's eye). It would be even more powerful if more than one of these crystals were in that piece of jewelry.
Take the piece of jewelry and hold it in your hand and with all your intention and will say, "May this crystal, or crystals, be my charm. Negativity, and negative energy, you can not harm". Wear the piece of jewelry to help you know you have protective energy around you as it is banished with the jewelry. Keep the jewelry on when you leave your house and are out in the public.
It is a good idea to redo the spell every month (during the full moon as it gives it more power).