If you want to learn defensive type magick, you might consider to start practicing shielding.
There are many methods of shielding. Here is one that can probably work for you in most cases.
Below is a visualization that can be adapted to your needs:
Try to give yourself at least 10 minutes to do this exercise. Begin by doing a relaxation exercise such as deep breathing with any grounding and centering technique you feel comfortable with.
Visualize a sphere of white light surrounding your body about arm's length from you. Imagine that surrounding this sphere is a grid of brilliant blue lines.
Surround this sphere with a wall of white light extending arm's length from the grid of blue lines. This wall has grids on both sides and locks into place with the first grid. Actually try to hear the click they make while locking in place with each other.
One more arm's length from this second grid, visualize another wall of light with a grid locking into place with the second grid. Again, hear the clicking sound they make together.
Surround this outer wall that is now three arm's lengths from your body with a brilliant blue flame about 6 inches thick. This is your flame of protection. Some associate this with the flame of archangel Michael.
Let this energy surround you for a few minutes. When you are ready, visualize this flame and grid system fading away from your mind's eye yet know that it is still there.
You can vary this technique to your comfort level. For instance, you don't have to use white light. Whatever color makes you feel safe is what you should use. You can even imagine a brick wall instead of a wall of light. You can also visualize a symbol such as a flaming pentagram, sword, cross, Thor's hammer, a shield, etc. to personalize it. Practice with your own protection rituals and see what is the best fit for you.
It is a good idea to do this every day especially if you are empathic. After steady practice, you might be surprised at how quickly you can put up your wall of protection. Psychic shielding along with grounding and centering are also important to do before more elaborate ritual and/or magic work where you are opening yourself to influences from the spiritual plane.