Use proper glassware
If you don't have stemmed beer glasses, at least offer to pour that can into a shaker pint glass.
Refill soft drinks for free
Iced tea and fountain drinks should always be bottomless.
Deliver drinks in a timely manner
Most people ordering drinks at a restaurant are considering how much time is left in their meal. If they order another beer when their entree arrives and it takes 15 minutes for that beer to make it to the table, the customer feels pressure to drink it too quickly.
An Irish goodbye is great for college parties and networking events, but, at a restaurant, the close of the transaction should be as friendly as the beginning. You shouldn't feel like you're dining and ditching. Unless you are. Which you shouldn't.
Dan Gentile is a staff writer on Thrillist's national food and drink team. He loves going to restaurants, especially when they have fancy soap. Follow him to the pleasant smell of cilantro and peppermint at @Dannosphere.