Write out the decision to be made in the top left corner of the page. Write the decision in the form of a question to help clarify the issue at hand. A "yes or no" question will help simplify the decision tree, but questions with other outcomes are acceptable as well. Draw a box around the written question to make it stand apart from the decision tree you will draw beneath. Explain to your listeners that the intent of the decision tree is to evaluate this question thoroughly.
Draw a vertical line from the decision box approximately three lines down the page. From the tip of this line draw a circle that is slightly smaller than the decision box. Explain to your listeners that this circle is for one possible outcome of the written question. From the center of the vertical line you drew, draw a horizontal line a few inches to the right. Beneath this line, draw an equal-sized circle parallel to the first outcome circle, and draw a vertical line to connect the top of the circle to the horizontal line above.
Discuss with your listeners the possible answers to the decision. If it is a "yes or no" question, write "yes" in one circle and "no" in the other. If the question requires more elaborate answers, discuss these different outcomes with your listeners, then paraphrase each outcome in the circles you drew. If needed, repeat Step 2 to add more circles for other possible outcomes.
Discuss the possible outcomes of each answer to the original decision. Draw these onto the decision tree in the same fashion that you added the circled answers in Step 2. Examples of outcomes may include things like monetary implications, time constraints or social effects concerning the decision.
Repeat Step 4 as needed to discuss and map out further implications to each outcome you added to the decision tree. Ensure that you discuss the issue thoroughly and get feedback from all of your listeners. This will give you the most complete decision tree possible once it is finished.
Review the decision tree with your listeners once all of the issues concerning the decision have been mapped out thoroughly. Expand on the main points that make up the decision tree by writing in parenthetical information outside of the circles, such as listing the exact monetary costs to expand on a point about the costs of the decision. This will give your listeners a complete visual representation of the decision and its possible outcomes and implications. Since they participated in its creation, your listeners will understand the meaning of each discussion point in the context of the issue. You will then be able to successfully discuss the final decision to be made.