Pay Me, I'm Irish

Hanafin's Pub also increases its bar space by shutting down the street in front of the bar and erecting two tents to house a music stage and beer bar. To ensure the crowd doesn't get too unruly, Hanafin pays the local police department overtime to patrol the crowd throughout the day.

"We have a good relationship with the New London police department, which is important. The city will let you do [a St. Patrick's Day party] every year, if it's done right," Hanafin says.

Take Care of Regulars

Any bar owner will tell you that regulars are vital to a successful bar or restaurant. With a day such as St. Patrick's Day, where the amount of customers can double or even triple, it's important to treat your regulars with the same good service, food and beverages they're used to.

One of Clancy's pet peeves is when bars increase prices on St. Patrick's Day to capitalize on the crowds.

"Why hit your regular customers like that? I don't believe in charging $4 for a bottle of beer one day, then cranking it up to $7 the next day," Clancy says. He makes it a point to keep prices the same as always. "The best way to capitalize on St. Patrick's Day is to make sure your regular customers have a good time and say, 'I'm glad I went to Foley's instead of someplace else.'"