For optimal freshness and safety, it's best to avoid prepping certain foods in advance. These include salads with dressing already applied (as they can become soggy), fried foods (which may become greasy and unappetizing), and dishes with delicate fresh herbs or greens added early (as they may wilt or lose flavor). Additionally, foods that require a crispy texture, like tempura or fresh fruits that brown quickly like apples and bananas, should be prepared fresh to maintain their quality.