The Psychic Shield is a much needed skill you will need. This involves visualizing a wall in your mind. Not a wall that keeps you in, but keeps others negativity out. How you achieve that distinction is something you need to figure out yourself. Every night before you go to bed gather energy and breathe slowly, while visualizing the wall forming in your head. Let the energy go once the wall has been formed.
The Inner eye is another skill you should learn. Visualize a closed eye in the middle of your mind. See the astral plane around you, and let the eye open slowly while you breathe and gather energy. The eye should glow with power when you are done. Let the energy go when finished. This one can be done anytime. If you have any problems with spirits, do the exercise, but visualize the eye closing. Be sure to do the opening of the eye before rituals.