Write out your hypothesis in a clear and direct manner. If it isn't something you can test with your own two hands that leads to a judgment one way or the other, you'll need to go back to the first step of the scientific method.
Brainstorm ideas for ways to test your hypothesis that are practical, observable and will have a clear outcome. Conducting an experiment is the next step in the method and should directly prove or disprove your hypothesis.
Create and execute the experiment. In most cases, you'll need a control to compare the results with. According to Science Buddies.org, "It is important for your experiment to be a fair test. A 'fair test' occurs when you change only one factor (variable) and keep all other conditions the same."
Analyze the results and all related or supporting data. Develop a conclusion based on the outcome of the experiment.
Decide whether the experiment proves or disproves your hypothesis. Either way, you've accomplished what you set out to do, which was testing your theory.