Some techniques to help someone practice telling funny jokes and riddles include memorizing the joke beforehand, identifying the key areas of the joke to emphasize and telling the joke to someone to receive feedback. It is also helpful to develop voices and personalities for the characters and to create an impact with the punchline.
Memorization of a joke is crucial because forgetting an aspect of the story, such as key details or the punch line, disrupts the flow and makes it harder for the audience to pay attention. Reading the joke several times and practicing telling it in sections without performing it helps commit the entire joke to memory. While improvisation is a major aspect of many comedy styles, it is best not to make up elements of a joke on the spot due to poor memorization.
Another tip is to determine what parts of the joke or riddle are important prior to telling it, such as the key points for setting up the punch line that should always remain the same. This helps the comedian identify any opportunities to use accents or visual gags to make the characters seem more realistic. Practicing in front of another person is also helpful because it not only helps the comedian become more comfortable with an audience but allows for immediate feedback on areas that need improving.