Call ahead and ask if the restaurant has special menus. Select single-item, identifiable foods rather than combinations. Plain broiled meats, baked potato, and green salad can be ordered without salt. Ask for oil and vinegar to use on the green salad or carry your own dressing with you. Ask for a wedge of lemon and use lemon juice on your salad or other vegetables.
Many restaurants use packets of lemon juice with a preservative containing sodium.
Avoid gravies, sauces, catsup, and mustard. These are high in sodium. Choose fresh vegetables rather than cooked ones. Canned vegetables contain salt. Restaurants use salt and often monosodium glutamate to season cooked vegetables.