Writing what you know doesn't mean that autobiographies are the only thing you should write. Shakespeare, for example, wasn't a prince but many of his plays such as "Hamlet," "Henry V" and "King Lear" feature royalty. However, they are rich with emotions such as love, hatred, jealousy, rage and envy. Let your experiences with strong emotions and conflict inspire your work.
Strong plays explore topics that the playwright finds exciting or interesting. For example, Michael Frayn's "Copenhagen" is about a historic meeting between physicists Niels Bohr and Werner Heisenberg. David Auburn's "Proof" takes its audience into the world of advanced mathematics. History, science, religion, mythology and even the news can generate ideas for a play.
Memorable plays are about characters with both strengths and weaknesses. Think about yourself to discover your strengths and weaknesses. Consider flaws that your friends and family have. As you create characters for your play, give them characteristics you've seen in yourself and others. For example, if someone you know chews their nails, then take note of it -- it can be a nuance to one of the characters in your play. Or maybe your play's antagonist smokes. These details will help craft realistic characters.
Plays tell stories with dialogue. The Greek playwrights and Shakespeare wrote in poetic, stylized language. However, contemporary playwrights such as David Mamet, Harold Pinter and Sam Sheppard look for the rhythms and poetry of everyday speech. Spend time at a mall, park, cafe or other public place. Close your eyes and listen to the conservations around you. You'll note whether or not people speak in complete sentences or fragments -- and whether speakers take turns or overlap.
Act one introduces the protagonist and the conflict he will face. It could be caused by an internal struggle, a rivalry with another character, a force of nature, a problem with society, technology or even destiny. Some dramas combine several different conflicts. In the "Star Wars" films, for example, Luke wages war with the Galactic Empire while facing temptation from the dark side of the Force.
Act two places the characters in the worst peril they could possibly face. Examples are the segment of "Star Wars" when the heroes are trapped on board the Death Star -- or when Rose and Jack are trapped below decks as the Titanic sinks. Of course, it doesn't have to be that melodramatic. For example, a play aimed at children might have a young protagonist climb a tree and get stuck.
The conflict is resolved in act three. Firemen rescue a child from a tree. Luke Skywalker destroys the Death Star. Rose escapes the Titanic. However, act three should also show the audience how the characters changed. Luke Skywalker is ready to train as a Jedi. Rose places little value on material goods. The child learns not to climb trees without adult supervision.