Whatever raw vegetables you like are fair game for your salad, AndhraKing. I use all kinds of lettuce, spinach, cabbage, kale, etc., whatever is on hand. I often add tomato, cucumber, celery, carrot, raw zucchini, broccoli or cauliflower florets and/or whatever else is on hand.
Since I'm a mayonnaise person, I don't know any good olive oil dressings for you, but you can experiment with combinations of oil & different kinds of vinegar.
Other good additions to a vegetable salad are nuts, seeds & olives . . . I have used sliced almonds, piñon nuts, sunflower seeds, etc., - walnuts & pecans or good too . . . and if you care to include any protein in your salad, you can always add grated cheese and/or chopped hard-cooked egg.