If you know you are going to be exposed to a lot of people or a strong projector (person who broadcasts loudly) You can do a meditation beforehand. During this meditation you can build a barrier. Visualize energy that starts glowing from your Solar Chakra (your solar plexus) and visualize it surrounding you into you can see a bubble that expands past your body by a few inches. It may take some time to learn to build it strong enough and some emotions may come through still but hopefully muffled. I went to a grocery store yesterday, my first time in a grocery store in over a year, I did not expect how hard i was going to be hit. With Thanksgiving, I didn't shield, and the store was packed with people stressing over the holiday, trying to pick-up last-minute ingredients, stress of having family staying with them and much more. Even some annoyed with me because i move slowly and me and my walker take up so much space. I hope this method helps you.

I do very similar to what Dyrewitch explained. It actually came to me as I was drifting off into a nap one day. Like Goddess was giving me a message she asked have you realized that you get very tired after teaching? I answered yes, one or two hours of teaching with a client you are absorbing their emotions and it’s draining your energy. She said as I meditate before class but up a thin silvery shield of protection so that their energy will bounce off of you instead of you absorbing it. I love my clients but each have things in life that does weigh on them. I can say I’m noticing a big difference since starting it.

I meditate as well. I also envision a protective shield around me. If I am uncomfortable with someone or a situation, I put up my shield. I even feel better if I put up my shield in crowds like a wall of protection around me.
The other thing that is really key for me is too make sure I balance my me time versus being with people time. Really, more me time than people time. I just need my me time to recharge, especially if I know I am going into a toxic situation. You can also call upon your spirit animal. I have several, but I may call upon a lion or bear, one that can protect and shield me. I envision them getting in between me and what ever I need to shield my energy from.