There's only one tip you need to be a more efficient food service staff member: 3 in, 3 out.
Here's how it works:
When a customer asks you for something, like a refill, don't go back to get it immediately or you'll end up constantly running back and forth, getting things for the 3-4 tables you're probably working at that time. Instead, wait (only for a minute) until you need 3 things from the kitchen -- for example, a check, a refill, and an appetizer order. Go back to the kitchen and address those 3 things, and make sure not to leave the kitchen without 3 things to take back -- for example, a refill, a dessert menu, and a check. You'll be much more efficient and not running around grabbing items and wearing yourself out, and your customers won't notice if you do it efficiently.