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.
You must know your competition in and out. Keep your friends close, but keep your competitors closer. You need to know all the things that you learned about your customers except fill in the blank for each competitor on all of those above items. Learn how you are the same/ different. Learn the similarities/differences about each product and service you offer. Learn how they sell or promote their products /services.