Here is how it can be done 

1. Circumstance 

What to look for: 

• Find out what is the specific problem the Customer is trying to solve 
• How does he go about it? 
• Develop an In depth understanding of  where your product or service fits into the purchase journey 
• This can help you spot opportunities others are likely to miss

Example: Blood tests are required once in a while  for detection of infection but they are needed periodically for elderly people and patients with chronic health issues. Many diagnostic labs tap this particular segment for recurrent business by offering value added services specially for that Customer segment 

2. Context 

What to look for: 

• Customers are usually not conscious of how they do routine tasks with products
• So if the product or service is being put to multiple uses it may go unnoticed
• Be with the customer when they encounter a problem and watch how they try to solve it to locate fresh  opportunities 
• Engage in small sample contextual research

Example: Indian mobile users are often seen using missed calls as a way of communicating a request to talk. So, “Gives us a missed call and we will immediately attend to you” became a sales pitch to create selling opportunities 

3. Constraints 

What to look for: 

• Your Customer may be experiencing a barrier constraining consumption 
• Figure out ways why Customers are not using your product/service or using less of it and work to remove or ease the barriers to multiply selling opportunities

Example A salesperson selling high quality specialty chemicals may find smaller manufacturers not buying due to price inhibitions. In such cases, encouraging purchase of small lots for special production needs may improve sales and offtake

4. Compensating behaviours 

What to look for: 

• Customers may be using a product or service for solving a problem it was not designed for addressing 
• Understand the value of the product in usage to identify opportunities not spotted earlier

Example An application software firm selling accounting software, finds that its accounting package is mostly used only for tax computation by small businesses and rest of the features are not much used. This points to opportunities to sell them pure play tax management packages

5. Criteria 

What to look for: 

• What is the criteria Customers use in deciding to buy? 
• What are the functional, emotional, and social lenses they use to look at the product or service? 
• Develop a deep insight into what triggers a purchase and appeal to that criteria in developing the sales pitch to improve range selling opportunities

Example: A Relationship Manager offering paints can sell more of a specific category if she can understand if the real estate promoter’s buying preferences – Functional durability or appearance and aesthetics?

You can read the Harvard Business Review article here