Executive Summary: the marketing plan like all the documents that are submitted to established executive bodies must begin with a brief summary of the whole plan, with basic numerical data and info. Mission and Vision: the marketing plan includes the company's "reason of existence", values and its future intentions and strategic approach.
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.