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.
Marketing services go far beyond keyword research and website optimization. It can include everything from brand development, SEO consultation, telemarketing services, email marketing, white papers, publishing and more. A marketing plan doesn't create a path from point A to Point B; it takes a dynamic approach to identifying the influences on your demographic to then create a multi_channel marketing web that is specific to your brand, product or service.