5. Not use Swiss cheese
Technically you can use a few different kinds of cheese on your steak: American, sharp or mild provolone, and Cheez Whiz (yes, it's cheese!) are all acceptable options. Swiss cheese is meant for ham sandwiches and mice. Oh, and to ensure properly level of melt, the cheese should be added right before the meat is done cooking.
6. Allow onions (if fried)
"Wit' or wit'out?" That’s the prompt most folks expect when ordering a Philly cheesesteak and honestly, they do benefit from some freshly fried white or yellow onions. Just don’t caramelize them -- you want the onions to still have a little bit of bite. Raw onions would also be out of place on regular cheesesteak but can be added to a hoagie, along with lettuce, tomato, pickles, and oregano.