What type of orthotics should I use as a hostess with flat feet who stands all day?

I work as a hostess at a local restaurant, and it's part of my job to stand all day and walk customers to their tables. I also have flat feet, so all of this culminates into very painful feet throughout and after my work day. A friend of mine recommended I use orthotics, but I don't know which kind to get since I have flat feet. Anyone have any advice?