I use pendulums for divination they're really simple and effective. You're basically allowing your higher self to answer the questions.
You can use anything thats a weigh at the end of a chain, a conker, nut, anything at the end of a string.
First of all you need to clarify which way is yes and which way is no, its best that you choose the directions (example forward and back like a head nodding 'yes' side to side 'no') ask the pendulum a few simple obvious questions that you know the answer to for example is my hair blonde, are my eyes blue etc.
As for the protection mantra i'd think something up your self, its a lot more personal and effective when you do this. Look to poems and stuff for inspo and start rhyming.