1. Share what you love! If you have a favorite cocktail that is your 'go to' for a special occasion, serve that! Your guests will appreciate the personal touch, even when it comes to the alcohol you provide. If you have never cared for a French 75, but just like the name - pass on featuring that concoction and try some alternatives like the French 77. You may like it better and you still get the cute title!
2. Keep it simple! The fewer ingredients a bartender uses the better so that the drinks can be served faster. If you love a complex drink try and find a cheat to make it faster. For example, I have a couple serving mojitos this summer as their signature cocktail, but to save time they are pre mixing the sugar, lime and soda so that the bartender does not have to muddle each individual drink.
And I get the question all the time, 'Can we have a beer as a signature drink?' Sure! My groom Sunny was known for always having a Rainier when out and about, so he made that his signature drink and his buddies loved it.
3. Spruce it up a bit! Have the signature drinks stand out by using specialty glassware, add accouterments such as a skewer with fruit, mint leaves or unique design or by simply serving it with a pretty paper straw. If you are featuring a Moscow Mule, go the extra mile and make sure the caterer has copper cups. Touches like this make the drink feel fancy and who doesn't like feeling a bit fancy:)
4. Signage! Ensure your guests know they are enjoying a signature cocktail by putting up a sign at the bar. This helps distinguish 'his and hers', you can share the history of why it is important and adding unique signage is another personal detail that adds to the look of the event. The personal touch of a signature drink sign is also a great way to add color and humor to the bar.
5. You don't have to break the bank to add a signature cocktail! If the ingredients are pricey you can limit the service to just the cocktail hour instead of serving the drink all night. Or as an alternative, I've had many signature cocktails be served when guests arrive before the ceremony so they can enjoy a drink while the bride & groom exchange their vows. And for couples who want to have a beer and wine only event, this is a great way to add a liquor drink without having to provide a full bar.
6. Communicate with your caterer! Make sure to let them know in advance that you are providing a signature cocktail, what the recipe is and how many you estimate to serve (an hours worth, all night service, one round, etc). If you are providing the ingredients consult with them before purchasing the alcohol. Even though buying a larger bottle is cost effective, you don't want to make it awkward for service. Large bottles are harder to pour and slow down your bar line. And running out of garnish would be most unfortunate so definitely consult with them prior to purchasing the items.
I hope these tips have helped! And when in doubt, enjoy a night out and taste test until you have the perfect cocktail to serve your guests!