Reddit reviews The Joy of Mixology, Revised and Updated Edition: The Consummate Guide to the Bartender's Craft

I typically point newcomers to drinkskool.com. It was developed by big names in the industry that also put the now famous BarSmarts programs together. It's completely free and a great place to start. After that, I recommend Jeff Morgenthaler's The Bar Book. Jeff says he wrote his book as a followup to Gaz Regan's The Joy of Mixology. So between these three resources and some experience, you'll be ready to tackle more advanced work, like Death & Co and Cocktail Codex.

~Good luck & Have fun!