It's the quintessential cocktail to many. So simple but truly so good when done well. Like most classics, it's been changed and butchered in more ways than one. Everyone's recipe seems to differ slightly; like whether to use Demerara syrup or muddle a sugar cube, or to add soda water, etc. However, the origin of the O.F. came from people asking for just a simple, "old fashioned" cocktail. As long as you're working with whiskey, bitters and a bit of sugar, you should be okay.
The Old Fashioned is a great starting point for home bartenders. Once you have it down, start swapping out ingredients (like using aged rum instead of whiskey). It's a great cocktail to help you learn how to create your own drinks.
2 oz rye whiskey
1 tsp Demerara syrup (or simple syrup will work in a pinch)
3 dashes of aromatic bitters
2 dashes of orange bitters
Garnish: orange zest
Add all ingredients to a mixing glass and stir with ice until chilled. Strain into a rocks glass over one large ice cube. Take your orange zest and gently express it over the top of the glass, allowing the fresh citrus oils to fall into your beverage. Rim the glass with the zest before dropping it into the drink.