You can't do a marketing plan without getting many people involved. No matter what your size, get feedback from all parts of your company: finance, manufacturing, personnel, supply and so on--in addition to marketing itself. This is especially important because it will take all aspects of your company to make your marketing plan work. Your key people can provide realistic input on what's achievable and how your goals can be reached, and they can share any insights they have on any potential, as-yet-unrealized marketing opportunities, adding another dimension to your plan. If you're essentially a one-person management operation, you'll have to wear all your hats at one time--but at least the meetings will be short!
Company operational instructions: Your child's first bike and your new VCR came with a set of instructions, and your company is far more complicated to put together and run than either of them. Your marketing plan is a step-by-step guide for your company's success. It's more important than a vision statement. To put together a genuine marketing plan, you have to assess your company from top to bottom and make sure all the pieces are working together in the best way. What do you want to do with this enterprise you call the company in the coming year? Consider it a to-do list on a grand scale. It assigns specific tasks for the year.