It ultimately depends on your own body and how it reacts to various foods. For instance, some people will swear by gargling with apple cider vinegar, while others will have visions of acid reflux dancing in their heads if they did that.
The important thing to keep in mind is that you want to stay hydrated, so avoid foods that typically make you feel thirsty. For many people this will mean avoiding things like caffeine, alcohol, or anything high in sodium or sugar.