"L’addition s'il vous plaît" ("Check, please"), "Quel est le plat du jour" ("What's the dish of the day"), "J'ai une réservation au nom de Camille Chevalier-Karfis" (I have a reservation booked under + your name)...
Practice simple phrases like these, so they come naturally to you and you don't have to struggle with them. It will give you more time to think about the rest of what you'd like to say. You will find all these expressions in my French audio books, which recreates modern, realistic French conversations on everyday topics like going to a restaurant, asking for directions, going shopping etc...
