Marketing & Advertising mentor Jay Conrad Levinson responds:
It's easier to create a first-rate marketing plan than you think. Keep it brief and simple. I recommend a seven-sentence plan.

The first sentence tells the purpose of your marketing, plain and simple. The second tells the benefits that your customers will derive from your product or service. The third explains your target audience. The fourth, which is the only long sentence and should be a list, lists the marketing weapons you'll be using. The fifth sentence states your niche in the marketplace -- your positioning compared with all competitors'. The sixth describes your company identity, the real personality of your company. And the seventh sentence tells your budget, which should be expressed as a percentage of your projected gross sales.

You can add as much documentation to your plan as you wish, but keep it to seven sentences at the outset. That not only forces you to focus on your marketing, but also makes it easy for others to read your plan and get your drift.

For more in-depth marketing plan guidelines from Levinson, read the Inc. magazine article " Plan of Attack".