Strategy _ similar to business strategy, marketing plan will capture strategies required to support your business strategy. For example if your business goal is to achieve 20% increase in sales, your marketing strategy would be to 1) introduce new product, 2) increase price for premium offerings, 3) recruit more distributors and offer commission scheme and so on. Strategy is king. When you can see your business in totality, I can assure you that you will find it easier to manoeuvre. Marketing plan is the place to address all these issues.
Customer Segment _ this is talked about most of the time, but let's accept the fact that today's customers are fragmented to smaller niches. Your product and service will not be consumed by only one segment and at critical mass. it is likely to be consumed by smaller segment and multi. No more critical mass, but rather a solid spread of niches. For example, who buys iPod's today? If Apple only think about yuppies they are making a big mistake because apparently iPod is also used by women and people with active lifestyle. Another example, who buys from hypermarket? If hypermarket only focuses on households they may not survive or be successful like today. Hypermarket main segment is actually small business restaurant operators that buy in larger quantity compare to households and on daily basis. I've been there, I know! LOL