A spec card that a new bartender can't read is not a spec card. It's a test.
I've seen specs written in parts instead of measurements, specs that list technique as "shake well," specs that include the bartender's inspiration for the drink and the flavor journey it's supposed to evoke. None of that helps someone make the drink correctly at 10 p.m. on a Saturday when they're three tickets deep and looking for a reference fast.
Ingredients in pour order. The order matters because it's the order the bartender builds the drink. Start with the least expensive ingredient if it's a shaken build where waste is possible from a bad taste-test. For most cocktails, the working order is spirit, modifier, sweetener, citrus. Write them in the sequence they go in the tin or glass.
Measurements in ounces. Not parts. Not dashes (unless it's genuinely a dash by convention). Not "a generous pour." 1.5 oz, 0.75 oz, 0.25 oz. The new bartender has a jigger. Give them a number they can use with it. If you write "1 part," you're leaving interpretation to someone who is still learning.
Build technique named explicitly. Stir. Shake. Build in glass. Flash blend. One word or two. Do not describe the technique in prose. If a bartender doesn't know how to stir a cocktail, that's a different training problem that the spec card cannot solve.
Glass type and ice. One line. "Coupe, no ice" or "Rocks glass, one large cube" or "Highball, cubed ice." This line eliminates one of the most common plating mistakes: the right drink in the wrong vessel.
Garnish with prep method. "Lemon twist, expressed" or "Orange wheel, half" or "Mint sprig, slapped." The prep method matters. A lemon peel that's expressed versus one that's placed on the rim is a different drink. Put the method on the card.
What to leave off: origin story, flavor notes, the ingredient sourcing story, the bartender's personal connection to the recipe. These go in a training document or a menu description. Not on the spec card. Every unnecessary word is information the bartender has to read past to find what they need.
One cocktail per card. A card with four cocktails on it gets skipped when someone is in a hurry. One card, one drink.
Photo on the back. The finished drink, plated and garnished correctly. A new bartender who has never made this cocktail should be able to flip the card and know exactly what the finished product looks like.
Print them, laminate them, keep them on the back bar. Not in a binder in the office. Behind the bar, where the person making drinks actually is.