Identify your use case: aperitif sips, an amaro-forward cocktail, or a cynar-based riff (like a bitter spritz).
Choose the substitute by bitterness target: match darkest/smoothest first (Averna/Braulio), or build with a lighter base (Aperol/vermouth + bitters).
Swap by ratio listed for your pick; if your substitute is sweeter or lighter, start at ¾ of the cynar amount and then increase.
Balance the rest of the drink: if you added extra bitter booster (bitters/gentian), cut simple syrup or sweet liqueur slightly.
Taste after mixing and adjust with one lever only (bitters for bitterness, citrus peel for brightness, or a small pinch of sugar for harshness).