Use your hands in each position and say silently or aloud once the word "Yeh-hah-shu-ah."Draw this figure in the four cardinal directions around you. Saying the word once for each direction.
You can make it small to be inconspicuous. If you look directly at a person the shield could be broken.
Length of duration will vary from 3 minutes minimum, 15 minutes minimum max. The more you use this cross the better you will get at its effectiveness. (wisdomsdoor.com)