As a serious applicant, you should know a lot about the restaurant. You should do your research and know approximately how many waitresses work there, what is a vision of a restaurant, what culture they try to create, etc.. Good applicant for a managerial position should notice all of this and should have an ability to talk about it openly in an interview.

On the top of that, you can compliment the quality of food and/or service, if you ate at the place before (what you should do).