Five pieces of equipment make almost any classic cocktail: a jigger, a Boston shaker, a Hawthorne strainer (plus a fine-mesh one), a mixing glass, and a bar spoon. Buy them once, buy them right, and you're done. Total spend, if you don't go silly: $70 to $120. About a round for four at a decent bar.
1. The jigger
Cocktails are ratios. A Daiquiri is 2:1:0.75 rum, lime, and sugar, and half an ounce off on any part breaks it. Eyeballing is how beginners think pros work. Pros measure, for hundreds of pours, until it's muscle memory.
Buy a Japanese-style jigger with 1 oz and 2 oz cones. Cocktail Kingdom's Leopold or Koriko are the standard, at $12 to $20. Skip the squat 1 oz / ½ oz tin jiggers from kitchen stores: the cones are too shallow to read, and the proportions are wrong for modern recipes.
Fill to the rim, not the line below it: "1 oz" means a slight meniscus. Pour over the tin, not the counter.
2. The Boston shaker
Kitchen stores sell the three-piece "cobbler" shaker with a built-in strainer cap. Skip it. The cap tends to freeze shut mid-shake, so you end up banging it on the counter. Its strainer holes are too coarse for fine-strained drinks and too fine for chunkier ones, and it doesn't hold much ice.
Every working bar uses a Boston: two tins, one inside the other (the older setup swaps the small tin for a pint glass). Buy a weighted tin-on-tin set: a 28 oz large tin and an 18 oz small one, from Cocktail Kingdom (Koriko) or restaurant supply, $20 to $30 for the pair. Skip glass-and-tin (the glass cracks) and rubber gaskets (they degrade).
Build in the small tin, ice the large one most of the way, and pour small into large. Set the small tin on top slightly off-center and tap it with the heel of your hand to seal. Shake hard until the tin is frosted and almost too cold to hold (Shake or Stir? has the timing). To open, hold the large tin in your weak hand and tap the seam with the heel of your strong one. It pops free.
3. Hawthorne strainer (plus fine strainer)
The Hawthorne is the spring-loaded strainer that sits on the tin and holds back ice and pulp. The fine-mesh strainer catches the tiny shards and citrus pulp that get past it. Skip the fine strainer and your sour wears a layer of grit.
Buy a tight-spring Hawthorne (Koriko or Cocktail Kingdom, $10 to $15); a loose spring lets ice chips through. Any 3-inch tea strainer works as the fine one, $5 to $10.
Fit the Hawthorne spring-side down into the large tin and hold the fine strainer over the glass, so the drink passes through both. Double-strain anything shaken with citrus or muddled ingredients. Stirred and built drinks only need the Hawthorne.
4. The mixing glass
Stirred drinks (Manhattan, Martini, Negroni) need cold and dilution without aeration. The spoon catches in a narrow shaker tin; a wide-bottomed mixing glass gives it room. Build the drink, add ice almost to the rim, stir (timing and technique are in Shake or Stir?), and strain through the Hawthorne.
Buy a 24 to 32 oz mixing glass with a spout, $20 to $35. The crosshatched "Yarai" pattern is common, and the etching helps your grip. Skip any with a built-in strainer hole; they're awkward to pour. A pint glass works fine while you're starting out. Plenty of bars stirred in one for years.
5. The bar spoon
Buy a 30 cm Japanese-style bar spoon with a teardrop counterweight and a twisted shaft, $5 to $10. The twist gives your fingers grip, so the spoon spins between them while your hand stays still. Skip short spoons, flat-disc "muddler" ends, and anything plastic.
Hold the shaft between your middle and ring fingers, thumb and index resting lightly near the top. To layer, hold the bowl upside down just above the lower liquid and pour the next one slowly over its back.
What you don't need yet
Someone will try to sell you a $200 starter kit. Skip most of it:
Muddlers. A wooden spoon's handle or a French rolling pin does the job for the occasional Mojito. Buy a real muddler once you make mint and berry drinks weekly.
Citrus presses. The hinged kind bartenders call a "Mexican elbow" (nobody's documented why) is genuinely useful, but a hand-squeeze works for one or two drinks. Buy one when you're juicing five or more limes at a time.
Channel knives and fancy peelers. A regular Y-peeler cuts great wide orange and lemon peels. The channel knife is a one-trick tool for thin spirals.
Smoking guns and clarification kits. Cool. Not for drinks 1 through 100.
Branded ice molds. Optional. A $10 silicone 2-inch cube tray does the job (Ice Matters). Branded "premium" ice ball makers: no.
Five tools, a bottle of decent Bourbon or Gin, and fresh citrus make a real bar. Still filling the bottle slot? Start with Whiskey Decoded.