Identify what you’re making (cocktail, spritz, or a glaze/marinade) and whether the recipe depends on bitterness vs aroma.
Start with the substitute ratio from the table above, then taste immediately and adjust: add a touch more if you need orange aroma, or add more bitterness with Angostura if you need sharper lift.
If your substitute is sweet (marmalade, sweet liqueur), reduce added sugar/juice in the recipe and thin it with a splash of water so it disperses evenly.
For non-alcohol swaps (tea concentrate), steep longer for bitterness and strain very fine before mixing.
Re-taste after dilution (ice in cocktails or cooling in glazes), because sweetness and bitterness perception changes as it chills.