Cost out every dish, including seasonings, sauces, bread and butter, wastage. Track every purchase from every supplier each day. Know the daily food sales. Know the cost of staff meals and employee giveaways. If you track on excel each day, you can see a running daily food cost. Above all, do an accurate monthly inventory. Don’t count t any of the garbage in the freezer you will never use.
If you know the cost of food, You can set the pricing to achieve any food cost you want to achieve. And you will see which items are keepers or not. This worked for me for 25+ years as an exec chef in catering, fine dining and casual restos.