There are two main reasons why you should write a business plan.
One objective of writing a plan is to present investors and lenders with a fully detailed profile of your company and how you operate. Lenders will often request a plan of this sort. This type of plan will have to be quite technical and we will cover it in the funding step here
The second reason to write a plan is to maintain a consistent vision and process. This business plan should be made specifically for you. We will call it the "internal business plan" Maintaining business focus is a must, and you will do this by setting goals, implementing strategies, predicting and managing expenses and maintaining consistency with your procedures. Staying consistent with your plan will help you gauge what works well and what needs to change. While many consultants will recommend having an in-depth, highly detailed plan (similar to the plan for funding) it really is not practical for your day to day process.
Internal business plan
Again, this plan should be as simple and relevant as possible. You are creating your own playbook, you want to be able to refer to this guide frequently and with ease. (tip: as your business grows, your game plan will change. You should rewrite your business plan when necessary but archive your old plans, this can help you figure out how your changes affected your business)
Here are some things you should include in your internal plan:
Write a summary of your company. Basically what you would have on your business card and a company description. What makes you the best option in the market?
Make a list of the products or services that you offer. (obviously you already know this, but write it down, as your business evolves, you may add or remove products / services. Remember this is your playbook!)
Identify your position in the market. Where in the market do you stand? Who are your target customers? Are you aiming to be a high-end source, a budget solution, a mid-market source? etc. (it is okay to cover multiple markets, just take note)
State your growth strategies. how do you plan on generating business? How do you plan on educating potential customers on your product or service? How will you market your business? (we discuss growth strategies here)
State your execution strategies. How will you provide and deliver the product or service to your customer? What systems will you use to ensure a smooth operation?
Create a management plan. How will you manage leads, active projects, open invoices, returns or remediations?
Estimate your expenses. Figure out how much it is going to cost to run your business, take into account everything from rent to paper clips. (tip: be really diligent tracking your expenses especially your first year in business, this is important and not as difficult as it may seem, we talk about expense tracking later)
Project numbers. Some consultants will recommend projecting your revenue. This is almost impossible to do and often useless. What you should however do is go over your estimated expenses and figure out what numbers you must reach to make your business profitable.
Full Business Plan
Your full business plan will be include all the specifics of your company. It is recommended to use an official template to ensure all your information is accounted for. The Law Depot has a great tool to help create an official business plan (and other legal documents) they provide information prompts and then will form an official, customized business plan for you. You can start creating a plan with them here: business plan creator.