A former Starbucks employee told Business Insider things you should never do at the coffee chain.
Don't collect a beverage without looking at the name on the cup.
Don't expect a free refill on every drink.
Avoid asking for drink add-ins after you've already paid.
Please don't leave a mess at the sugar and milk area.
Ordering off of the "secret menu" can be a real headache for baristas.
Don't get in line if you don't know what you want to order yet.