When audience members are seated close together on a curve, they can look to their left or right and see the faces of each person in the row. This togetherness allows laughter to pass immediately from one person to the other. Your word choice can be the key to creating a successful witty line or a dud. Cucumber is funnier than mushroom. Cupcake is funnier than pastry.
Turkey is a funnier word than loser.
Some humorists will disagree, but I say deliver your punch line to one person and make sure that person is going to laugh. You must punch the line out a little harder and with a slightly different voice than the rest of the joke. Lean into the microphone and say it louder and more clearly than you said the setup lines. If the audience does not hear the punch line, they are not going to laugh. You deliver the punch line to a person you know will laugh so that others will be positively influenced to laugh.