A business strategy is a continuous process, not a one-time exercise. A business plan's wording, formatting, and aesthetics aren't nearly as vital as its contents (though they're still crucial), and its contents should alter frequently. Actual businesses with real business plans examine and change their plans regularly.

Begin by making your plans.

The planning process, like everything else in the company, should follow the general business idea of gaining a return on investment of time, effort, and money. Focus on the business goal before seeking outside assistance.

If the goal of your business plan is to help you organize better by establishing strategy, tactics, milestones, metrics, and key projections, tracking results, and modifying frequently, the keys to success aren't the same as what you'd gain from hiring someone to do it for you.

1. Look for someone who is committed to the long haul.

Avoid hiring someone who thinks a business plan is a one-time product that should be used once and then thrown away. That is no longer the case in real-world company planning. In a couple of weeks, business plans become obsolete.

To make a plan useful, you must review results regularly, track progress, and revise frequently. So, you'll need someone to assist you, either by passing the plan on completely so you can easily review and revise it or by being available later to assist with review and revision.
Some business plan writing services have suggested coaches and see a similar relationship, while others do not. Avoid collaborating with anyone who will offer a plan then disappear.

2. Look for someone with relevant industry experience.

Given that the content of the plan is far more important than its appearance, you should seek assistance from someone with practical qualifications who can compare your plan to what the expertise indicates will occur.

You want somebody who can tell you if you are forecasting marketing expenses as too low to be realistic, or profits too high. You want someone who can tell you which metrics will be important. Those metrics are usually unique to your company, so you're probably already familiar with them.
Some businesses, for example, expand primarily on traffic, while others grow based on revenues per square foot, visits, leads, presentations, or whatever.

3. Find someone on your team who can help you.

Someone already on your team is the greatest place to look for someone who will be there for the long haul, knows your industry, and has relevant experience. Consider who you have on your team of managers and advisors.
Is there someone who could lead the task for you and take it over if you assume that writing a business plan is something that anyone who knows the industry can do—that it is not a specialized skill? If you answered yes, you're all set.