Learn the basics of story writing. Familiarize yourself with terms like resolution, falling action, climax (turning point), rising action and introduction. Study the basics of conflict, dialogue and character development.
Learn to tell a joke well. Imagination and timing are skills that require lots of practice.
Watch other TV sitcoms. Study how they introduce new characters and set up jokes. Figure out a theme that drives your story. Read scripts from famous sitcoms and watch how the story unfolds in live action. Scripts can often be found on websites dedicated to popular shows, like "Seinfeld" for example.
Study character development. Usually, characters have believable personalities in which comedy can be found. You can base characters on people you know. Alternatively, you can create characters based solely on ideas and your imagination. For example, the sitcom "3rd Rock from the Sun" featured alien personalities inhabiting human bodies on Earth.
Pick your setting. Successful sitcoms normally thrive in everyday locations. A familiar setting allows your audience to relate to the characters. Settings can include courtrooms, schools, office buildings and coffee shops. Preferably, your characters should have a centralize location that brings them together through the sitcom.
Brainstorm your sitcom. Take note of the names of places and characters. Start sketching a story board that outlines your conflict and resolution for the show's story. Write a short synopsis of the sitcom. Use this summary as part of your promotional materials when you go to sell your show to a television studio.
Begin writing the pilot or first episode. The pilot needs to entice the audience with conflicts and characters. The pilot is like a movie trailer; it needs to leave your audience wanting to see more.