Having to work at a bar on Christmas Eve or Christmas day, is very iffy. Some smaller local, neighborhood bars may fair well, because some of the customers have no family around and of course you know the local bar is a family of sorts. You can do okay, some times the regulars are out of town or have family IN town and can't get away for a drink.

Two things to help you foster a holiday tip are :

#1 Hang stockings behind the bar with each stocking having the name of the bartenders that work there on them. Customers will leave a holiday tip for the bartender in their stocking.

#2 You as the bartender give scratch off lotto tickets to customers as a gift. These are the perfect size to carry around and you are able to write the customers name on them off to the side, so it's personalized.