Design Process Map
Often, you may find that you'll need to revisit your design approach beginning at step 5 or 6 (as indicated in the pink arrows inside the larger circle.) At other times, you may need to start over completely at step 1: Identify the problem, because you may now have enough data to know that your original problem is not the 'underlying' cause. Adaptability is key with any new experience.
More information on the design process can be found: Design Process Resource