Identify the innovation and the aspects that make it an innovation. The important aspects of an innovation include complexity, how advantageous it is over other options and the obviousness of its advantages to the general population. For example, the light bulb is clearly more complex than its predecessors (e.g., oil lamps); it has the obvious advantage of lighting a larger area; and, while the technology itself is complex, the advantages are clear to the general public.
Analyze the process through which inventors pooled their ideas to create the innovation. Few innovations are created in a vacuum; they often involve several different individuals improving on the work of previous individuals. For example, while many consider Thomas Edison the inventor of the light bulb, the original idea for it actually dates back to Warren De la Rue in 1820.
Factor in time as an important element in considering the diffusion of an innovation. While the original idea for the light bulb dates back to 1820, it was not perfected until 1879. The time aspect of the diffusion of innovation also includes the time it takes for the idea to take hold in the general public; it still was not until the early 20th century that light bulbs became commercially viable.
Understand the importance of the social system in the diffusion of an innovation. This ties in to the second aspect of time. An innovation can not be considered fully diffused until it is accepted by the population as a whole.