The major purpose of energy shields is to protect oneself against negative energy from outside sources. Visualization and meditation is the best way to start creating energy shields. I found an article that should suit you fancy:
If you have any more questions, I be delighted to assist you to the best of my knowledge. Blessed be.
One has to strengthen the shield everyday to keep it solid. The two things I do is use Black Tourmaline or a Thoughtform to filter out the negativity so that way you don't have to do too much work.
I made a post here on Spells of Magic about what shields are and how to go about creating one. You can find it at https://www.spellsofmagic.com/read_post.html?post=912643