As an empath, I struggle in certain energetic situations. It isn't always large crowds. It could be one specific person that is negative or "throws" their energy around (or at you). Some days it feels like I am not meant to exist in a social world and would rather hole up in my bedroom. Since that isn't exactly an option (though I am working on it), I have learned that I needed a practice of energetic protection and cleansing (beyond Reiki).
To protect myself from everyone else's unwanted "crap" I have a little thing I do in the morning. My teacher taught me her protection and I modified it a little for myself. I see myself enveloped with light. Literally enveloped. My teacher suggested seeing a light surrounding myself but I find it easier to almost picture a sleeping bag that I step into and pull it over me like a hood. I picture it made of light. I mostly picture white light but some days it has been purple or more golden. I let me intuition guide me. I set the intention that this light will protect me from (I literally say this) everyone else's sh*t, keep my shit from them, and to only let love and light through. That's all I do.
Then after I am home from work I cleanse myself with Palo Santo spray I made from the essential oil. I have this 2 oz glass spray bottle that I filled a quarter of the way up with witch hazel (to distribute the oil evenly), 12 drops of palo santo oil, and the rest with distilled water. I shake it when I get home and spray all over myself.
I hope this helps any other empaths out there exist in the crazy energy of the world! Feel free to pass along any of your rituals to help others!