Generally, companies are broken down into four levels of hierarchy, the corporate, the division, the business unit and the product level. The overall plan of the company is designed at a corporate level. As part of this planning, each resource is allocated to each division of the company. Next, division level planning allocates resources to each business unit of the company. In addition, business unit planning designs a strategic plan for each business area, which determines each of the marketing objectives/goals, strategies and tactics, that have to be consistent with the overall strategic plan.
You need to know everything obtainable about your customers. This list will get you started. You will need their age, sex, marital status, income levels, education levels, geographic locations, where they shop, if they go to church, if they have kids, ages of children, political affiliation, what they like about your company, what they don't like, why they shop with you, what they value about your products/services, what they like the most/least about products/services, and whether prospects are unaware of your brand or products/services. Customers want you to know certain things about them and if you do, they will remain loyal to you as you take time to know them.