As a former olive hater, I can tell you that the variety of olive that you use matters. Green olives are milder and more citrusy—a good “beginner” olive, if you ask me. The recipes that call for green olives need an olive that is buttery and mild. Black olives like kalamata pack a salty punch and are often placed in recipes to give a small pop of flavor, something a green olive won’t quite do. It’s best to avoid substituting in this case. If you don’t love olives, feel free to leave them out.