One of the most common questions I get from business owners comes from people who sell their expertise for a living. These lawyers, web designers, public relations consultants, and plumbers often make a decent living, but usually the business consists of just them and maybe one or two helpers.

They struggle to grow because clients insist on dealing with the expert—understandably.

To scale up a knowledge-based business, you have to figure out how to impart your knowledge to employees so they can deliver the goods. But it can be difficult to condense years of school and on-the-job learning into a few weeks of employee training. The more specialized your knowledge, the harder it is to hand off work to juniors.

I have found the key to scaling up a service business can often be found in offering the service that prevents customers from having to call on your service in the first place. You have to shift from selling the fix to selling the prevention.

For example, it takes years for a dentist to acquire the education and experience to do a root canal, but it's relatively easy to train a hygienist to do a regularly scheduled cleaning. Fixing what is broken is typically a hard task to teach; however, preventing things from breaking in the first place can be easier to train others to do.

It's nearly effortless for a real estate manager to hire someone to clean the eaves trough once a month, but repairing the flooded basement that clogged gutters can cause can be quite complex.

For the master car mechanic, overhauling an engine that has seized up takes years of training, but preventing the problem by changing a customer's oil regularly is something a high school student can be taught to do.

For the IT services company, restoring a customer's network after a virus has invaded often takes the know-how of the boss. But preventing the virus by installing and monitoring the latest software patches is something a junior can easily be trained to do.

When you're selling your expertise, it can be tough to hire a team to do the work. As ironic as it sounds, sometimes the key to getting out of the doing is to offer the preventive service that can eliminate the need to call you in the first place.