It really depends on why you are writing the plan. If it's to seek investment, visit some venture capital sites, some will have guides or comments regarding what they want to see in a business plan. You may have to dig, but you'll find some good stuff. They typically don't care as much about pro-forma numbers because they know your guessing any way. If you're going after bank or family money, they'll probably be more interested in pro-forma stuff.
If you're going after investment, focus on the market and how you/your offering is uniquely qualified to capture significant share. Spend very little time on periphery stuff, investors don't really care about what type of copy machine you're planning on buying. They're also more concerned with the team vs. the product/service. Investors will always prefer an A team with a B offering vs. the other way around.
Personally I prefer a format that looks something like this...
I. Executive Summary
II. The Market
III. The Team
IV. The Solution
V. Strategic Plan
VI. Financial Plan
VII. Additional Information
This shouldn't be more the 10 pages.
This post was edited on 12/26 at 10:57 am