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.
Now for the good stuff. I am going to tell you how to set up a modern MLM marketing plan that actually works for you 24 hours a day 7 days a week. The first thing is to find a high quality network marketed product or service that you can be passionate about. Being passionate about it makes it much easier to stick with long enough to really learn about it and see the benefits. Your passion will be felt by those you talk to about your opportunity. Personally I am passionate about health and nutrition. That is why I market what I consider to be the highest quality nutritional products available.