Any tips for preparing tasty, healthy sandwiches?

Variety is best. Start with a whole grain moist bread or roll, use low fat cold cuts or lean cooked and chilled meats, add veggies. Besides lettuce and tomato, use sliced radishes or sliced peppers. Cucumber with dill dressing is interesting, Add celery, onion, and pickle relish to tuna with low fat salad dressing or plain yogurt, and add curry, raisins and grapes to diced chicken. Mustard is better than mayo.