My general rule of thumb for appearance is that I should look as if I could be in the restaurant dining (not working).
I want to be as close to an equal with my guests as possible, and much of that is determined by my appearance.
Obviously this will vary depending on restaurant, but if you're working in a more upscale restaurant, consider these shoes below.
*Surprisingly comfortable.
Non-slip Oxford Shoes
https://amzn.to/3U9GcfM