When I was 20~ish, I worked for a local "Ground Round" as a waiter. They had a bartending opening and the manager offered me the position. They had their own on-site training program that, in hindsight, was really spectacular.
Now being a bartender can be a lot of fun. It can also be an elaborate form of babysitting. Depending on your city/state, the laws may be in your favor or, as in my case, very much against you. Meaning, if someone looks fine, has a drink, leaves and causes an accident....you, the manager and the restaurant can all be held liable.
Its amazing but since people will ditch any form of responsibility, the legal system has found a way to sue anyone and everyone who has deeper pockets than the offender (if he/she is still alive).
So while its fun mixing, serving and entertaining...I cant emphasize enough to know the local laws. Being the "nice guy" who gives those "nice folks" one more round might be the same people trying to sue your brains out to save their butts from going to jail.