@Charred - I don’t know much about a marketing plan—but I think that in marketing branding has to be more important than anything else, especially in today’s business climate where everyone is online. It’s not so much differentiating the market which should be your primary concern, it should be differentiating yourself.
When I first started establishing my service business (software development) I stopped and asked myself what made me different from the average Joe Programmer. I had skill, but I wasn’t Bill Gates. I made a list of things that people who had worked with me had said about me and used these testimonies as attributes that set me apart from the competition.
I promoted these attributes in my advertising campaigns, and they helped to secure a lot of business from the start. Believe me, branding is everything.