Going undercover to shop your own store or business can reveal unique opportunities for improvement. And some of these insights can be key to building customer loyalty and unlocking sales.

I first learned about secret shopping, also known as mystery shopping, several years ago when my wife was hired by a major department store to help them improved their brick 'n' mortar retail operation. I'd previously thought that secret shopping was an employment scam (and in many cases it still is).

My wife's experience with the genuine article revealed a number of techniques that much smaller companies can use to improve their merchandising and correct the sales and customer service mistakes that are sabotaging their business.

For those that haven't heard of secret shopping, it's essentially having someone you hire go to your store (whether online or physical), interact with the sales team, make a purchase, and then provide a detailed report on their experience.

My wife's experience uncovered subtle, but important, issues with customer service. In one case, she had a single store whose staff was routinely reticent to engage with shoppers. They were friendly--but only when asked a direct question by the secret shopper.

On one shopping trip, the secret shopper browsed the store for 33 minutes before the first sale person approached to ask if she needed help. It's very likely that sales were walking out the door.

In other cases, staff seemed to prioritize merchandising and restocking over helping customers. Boxes of new merchandise blocked items on shelves or easy access to checkout.

Once you know about these problems, they have easy fixes. Following are four tips for creating your own secret shopper program:

1. Keep it secret.

The first key to secret shopping your business is that it needs to be a secret. That means no sharing with staff that a secret shopper will be coming in today.

Avoid the "Undercover Boss" approach of disguising yourself. Find a friend willing to visit, instead. You can later void their purchase or just let them keep whatever they buy as a reward for helping with your program.

The blind should be maintained throughout the purchase. If the shopping is done online, the billing method and shipping address should all be in the name of the unknown shopper.

2. Make the experience meaningful.

In order to provide insights that can help you improve your operation, the secret shopper interaction needs to be meaningful. Having your shopping spy whisk into your store, grab the first item they see, pay cash, and then slide out the door is very unlikely to surface much feedback.

Instead, ask your shopper to go into the store and browse a while. That way they can see how long it takes for someone to ask if they need help.

At some point, have them ask for advice under the ruse of buying a gift and not knowing the right size or style. Even a small interaction can help you better understand the experience of real customers. If your store is online, the interaction could be via chat or a question emailed to your team.

You can even have the secret shopper returning an item a day or two later with a perceived issue and see how it's handled.

3. Pay attention to the details.

Encourage your secret shopper to pay attention to the entire experience and then share those details in their report to you. When my wife was doing this for a living, she would first meet with store and regional managers to create a list of questions and things to watch for, and she would often work for hours compiling notes and creating a report.

If you're leveraging friends or colleagues, you'll need to keep it a bit lighter. Still, be sure they note whether the store was busy, how long it took for them to be helped (and whether it felt too long), the condition of the store, the demeanor of employees, the names of staff they spoke with, and other details.

If you're unsure of what to focus on, read the reviews past customers have left on review sites and see if there are any running themes.

4. Focus on teachable moments.

Secret shopping should not be a "gotcha" that turns into negative discussions with staff. Doing that will destroy team morale. Instead, try to distill the feedback into a few positive steps that you can take to improve your business.

Some may be training related to provide more product knowledge or improve communication skills. Others could suggest changes in how you merchandise or package your products.

Whatever it is, try to involve the team in finding solutions and you may find that secret shopping becomes a secret weapon for making your store a customer favorite.