I'm going out on a limb but I bet your first 21 year old drink will not be your first drink. Have what you always drink, drink in moderation, renew your vow never to drink and drive-you have made that vow haven`t you- and have good memories of you first night drinking as a responsible adult.
As far as cocktails Gary and Mardee Regan have a book called New Classic Cocktails I suggest you get a copy and read through it. Something will click with you, when one does try it.
I first met Gary back in the mid 70`s, he was the new kid at a place that was one of my regular stops. I was running a mini group of places on NYC East Side I think we had about 4 then and was alway on the look for bartenders. We never worked together but I always enjoyed stoping in when he was working. A good bartender can make a scotch and water into something special, from the first sip of my Dewars and water I knew he had what it takes. The art of making a simple highball stand apart from every one you had before is the sign of a great bartender. He takes that same simple purity to wonderful places with this collection of must try drinks.
I would suggest you start tasting the base spirits on one rock with a thimble of water.
Gin Vodka Scotch Rye Bourbon Rum Brandy to get used to their pure taste. I suggest one of the traditional "good brands" the best selling "call" brands. They are available every where and are kind of middle of the road tasting giving you an idea of the benchmark flavors of the spirit.
The best way to pick the brand is ask the barkeep to choose one for you. Tell them that you are trying to get a feel for what each spirit tastes like. Bartenders love to help you become an educated customer.
There is nothing better than having a good bartender make you their pet project.
Tipps is spelled TIPPS it means to Insure Prompt Personable Service. While undertipping is frowned upon
the sincerity of the thank you that goes with the tip is the measure of it`s value not the President on it.
Enjoy
I did mention you should never drink and drive didn't I.