Decide on the process of flowcharting.
Define the boundaries of the process– the beginning and the end.
Describe the beginning step of the process in an oval.
Ask yourself ”what happens next?” and add the step to the flowchart as a rectangle. Continue mapping out the steps as rectangles connected by one-way arrows.
When a decision point is reached, write the decision in the form of a question in a diamond and develop the “yes” and “no” paths. Each yes/no path should re-enter the process or exit somewhere.
Repeat steps 4 and 5 until the last step in the process is reached.
Describe the ending boundary/step in an oval.
When drawing a flowcharting, constantly ask “what happens next,” “is there a decision made at this point,” “does this reflect reality,” “who else knows this process” etc. When possible, do a walk-through of the process to see if any steps have been left out or extras added that should not be there. The key is not to draw a flowchart representing how the process is supposed to operate but to determine how it actually does operate. A good flowchart of a bad process will show how illogical or wasteful some of the steps or branches are.
The best way to illustrate the use of these guidelines is to look at a simple example (see below) and follow how each step has been applied.
The first step is to identify the process to flowchart and to give the chart a title. In this case, it is “how to fill the car’s petrol tank.”
Begin to draw the chart by first describing the event which initiates the process (the “trigger”). In the example, this is “low petrol warning light comes on.”
Then note down each successive action taken. Actions should be described in as few words as possible, but make sure the description is not ambiguous or unclear.
When you reach a point at which the flowchart branches into a number of alternatives and the resulting complexity threatens to overwhelm the exercise, choose the most important alternative to continuing flowcharting with. The others can simply be terminated and dealt with in separate flowcharts. Such a point is illustrated in the example where a decision is required on how much petrol is to be put in the tank.
Often you may need to make cross-references to important supporting information (in this example, cross-references may be made to, say, a table of preferred brands of petrol, or to a list of cars able to use unleaded petrol).
Continue describing each event, action or decision as it occurs in sequence until the process is concluded. In the example, this point is reached when the petrol is paid for, the tank is recharged and you are ready to drive off.