Know the play inside and out. Do not skimp on reading the play; read it at least five or six times before auditions. Because it is so short, you could easily read the play ten or fifteen times. By doing this, you get a very specific idea of the plot and how the play moves, as well specific prop and costume requirements. You will also grow an insight into each of the characters.
Write up a production concept which states your vision for the play. This is a guide for the design and direction. "Trifles" could be staged in a backyard with minimal props or on an elaborately-designed set. The script calls for a realistically furnished house. However, the text is wide open for artistic interpretation. A realistic staging transports the audience to the specific time and place of the play. A stripped-down concept focuses more on the text or teases out specific themes.
Gather the required props. Glaspell's story revolves around certain items that can't really be ignored, such as a bird cage. You don't need to shell out the money for a real birdcage, though, if realism isn't your concept. Construct a minimalist bird cage out of wire or write "cage" on a piece of paper. Let the text and your concept guide you.
Rehearse with the actors to figure out specific staging. Since "Trifles" is realistic, the actors' organic instincts will provide a great skeleton for staging. As the director, your job is to ensure the stage pictures are striking and everyone in the audience can see everything that happens on stage.
Revisit the text and your concept. See how well your staging moves the story along. Glaspell's play is dramatic and powerful; a good production of "Trifles" should never feel static. Try having the actors get more physical or use different stage levels (remember that stairs are called for in the script). All the on-stage action must be motivated by Glaspell's characters. As rehearsals continue, restage anything that feels false.