A non-disclosure agreement would be the customary way of protecting your idea. An idea for a way to improve a company's services is probably not something that can be protected by a copyright. Obtaining a patent for a business method is currently much more difficult than it used to be could also protect your idea.
This said, enforcing a non-disclosure agreement or a patent in court is expensive, slow and unpredictable. Often judges deny relief for one of many available reasons.
Sometimes people use trademarks to certify businesses that are conducted according to their methods, which help the certified businesses win customers because people learn to appreciate those methods.
The details of the method matter to what makes sense as a business model. Many people are employed by the hour as consultants, and if a considerable amount of time is necessary to teach people the business method, and it isn't easy for other people to be as good at teaching it as you are, hourly compensation until it is implemented could work to monetize your idea.
For example, as a lawyer, I can make a living telling people about law related ways to deal with their business issues and despite the fact that the underlying knowledge that I am providing has no intellectual property protection and is mostly in the public domain, I can do so because the relevant information its difficult for an average person to locate and apply, and it often takes a lot of time to implement ideas based upon this knowledge.