But actually this is the fun of appetizers. They are supposed to be small amounts of food. A tasteful surprise. One more chance for your palate to experience awesome flavors without making you too full to enjoy the subsequent surprises, a salad or soup perhaps, main course and desert. And how about finishing your meal with coffee, tea or liqueur? mmmmm...
Appetizers can be served at the table or before seating while guests are waiting for the meal. If you are serving before dinner than usually you will have more than one kind, three would be fine. The amount will vary according to how long the guests will have to wait for the meal.
You can also have a get together with just appetizers. For a small group of guests you can have 3 or 4 different kinds of dips with crackers, veggies and chips.