If you wish to include a list of cast and crew, get the proper spelling and job title of every person involved with the production. Check with the producer to determine the order in which you should list the cast and crew. This may seem like a trivial detail, but in the world of artistic egos, enemies can be made from such things, so let the producer or director determine which characters are leads and in what order their name should appear. As a personal touch you can add photos and bios of the cast and/or crew.
Offer an overview that lists the acts in the play in the correct order and designates when the intermission will occur. The playbill can relay any relevant information that would be helpful to the audience such as how long the intermission will be (generally 15 minutes) and if there are concessions available. Other helpful information to include is your theater's policy on photo or video cameras, or information about parking policies, ticket refunds and upcoming productions.
Finally, the playbill is a good location for information about the background of the production. You can include a facts about the author, composer or director. Many operas, especially those sung in a foreign language, offer a play-by-play synopsis of the action during each scene. Other plays give a brief overview of the narrative as a teaser to the action that is about to occur.
The cover of the playbill might display a photo or graphic relevant to the play. A shot from rehearsal or a hand-drawn picture depicting a main scene will do nicely. Keep in mind that many actors and crew (and their friends and family) keep their playbills as keepsakes and collect the signatures of everyone involved, so your creation could be around for a very long time.