By this you are beginning the path of Perect Love and Perfect Trust. In other words, be patient with your teacher, yourself, and your talents. Continue to do that and let your heart and mind both be open to the possibilities, but listen to your intuition also, for your own safety. This is also part of Trust and Love. As far as shielding, grounding, centering, and meditating - I believe I can help you here.
Lets try some guided meditation exercises.
I'll give you a basic outline that you can personalize and embellish for yourself and your own needs. Create an environment for yourself - somewhere safe and quiet where you will be undisturbed for the period of the exercise. You might want to make the space more sacred and pleasant for yourself by burning incense, lighting candles, maybe even playing soft music. Close your eyes. Imagine your feet are turning to tree roots going deep into the Earth, anchoring you, grounding you, pulling up energy from deep wellsprings full of light and love.