I have a couple of methods I use, but it's important to note that the majority of spirits at my work are neutral to benevolent and are passing through instead of sticking around to become a staple of the place. (I work in the funeral industry, for clarification.) So, I generally have less to fear as far as malevolent entities go.
However, I think some of my practices might be a good foundation for protecting yourself, though you may end up wanting to build upon it, and it includes several methods. First method is based in grounding, visualization, and energy work. One of my personal methods when I feel something may be using me for energy is to imagine my figure lit up as a solid figure of light. Then I imagine a dark gray stone filling in and covering the light from my head to my toe, protecting the light. You can imagine it as stone or brick or whatever else you feel is most effective for you.
The second method is color magic. Wear lots of black, gray, brown, or colors that you personally associate with being protective. For example, some people associate red with "warding off" or a warning, since bright red can be exactly that in nature in some instances. You can also use visualization as you get dressed for whatever you wear to become your suit of armor. As for when you come home, you can also use a lint roller, lint brush, or a ring of duct tape on your hand to help lift both fuzz and anything negative that may have clung to you during your shift. If you find you are often spiritually sensitive, you may want to look into discreet ways to veil, as many empaths and some mediums find it helpful.
Creating a sigil for this purpose can also help you. I have a catch all sort of sigil, made from the phrase "I am protected from harm and ill-intent." However, it doesn't hurt to get more specific if you feel that is too broad. Making a sigil with something like the phrase "I am protected from spirits that wish to do my harm" or something along those lines could be useful. You could then have it on slips of paper and put it in your pockets, embroider it on the inside of clothing. You could put lotion on your body in the shape of the sigil and then rub it in to activate it. You could write it on your skin in pen or paint. (please be safe, ink poisoning is real)
Crystals and stones can also be helpful. I've personally been carrying hematite, as that's what I have a decent amount of right now, though I'm looking to try and get black tourmaline or black obsidian. You can also use a nice rock you've found or even a piece of glass (like those little round pebbles in home decor stores) and meditate with it, charging it full of your energy with the intent of it protecting you.
You can also use herbs. Some people carry sachets of protective herbs in their bags, pockets, and hats. You could use herbs you've researched and made sure are safe and put them in your coffee or hot tea, and have your drink before you go into work. (Common advice I believe is to stir clockwise.) Or, you can cook with these herbs. (Garlic is usually pretty good as a protective food item, just be aware if you're like me and have a tendency to...sweat the smell out if you've had a lot.)
Ultimately, you'll have to find what works for you, but these are just a few things I use to help me.
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