The e_marketing plan is built exactly on the same principles as the classical plan. There is no different approach, but there might be some formal differences given by the uniqueness of the internet environment. Many of these differences come from the necessity to ensure a high rate of responsiveness from the customers, since the e_world is moving faster and requires faster reaction from its companies, compared to the traditional offline marketplace.
To make an effective plan, there is a famous rule called 4P's. Here, P's stand for Price, Product, Promotion and Placement. In this another P is added called People. Today while doing digital marketing or the traditional marketing one should understand people or the customers you are dealing with. It's important to figure out what is significant for the business, and later make a plan accordingly.