Most people who attempt to market on Facebook fail miserable simply because they do not know the dos and don;t of facebook marketing.
Social media marketing is a very special arena and different than all other marketing out there.
When marketing on Facebook you need to have a real respect and understanding for your prospects.
You are building a tribe of people that will follow you and buy from you again and again so you need to keep this in mind when putting out content and posts.
Check out this talk to learn more on how to maneuver your Facebook marketing.