GW Rule #34

It is good manners to prefer them to whom we speak before ourselves especially if they be above us with whom in no sort we ought to begin.

PEEVES

It’s good form to let others go first. Pause your paws!

MADAMA

You’ll never go wrong by being kind to let others go first.

SANDRA

Think about it.  Let them go first: walking through a door, be served at a table, choose where they want to sit, get into a car, have seconds at a meal, and on it goes.  This is always true if they are elderly, have accessibility issues, are a guest, at a cash register with fewer items, and perhaps are the new person.