A case study should help a potential customer understand how your business approaches a real problem. That purpose gets lost when the story becomes a collection of unsupported claims or a result attributed entirely to work that was only one part of a larger effort.
You can write a useful case study without a dramatic revenue figure. Clear context and honest evidence often answer more of a buyer's questions.
Agree on what can be shared
Confirm permission to identify the customer, show the work, use their logo, and publish a quotation. Some projects involve confidential information or contractual restrictions. Approval of the work itself does not automatically establish permission to use it in marketing.
Keep a record of the approved material and the person who authorized it. If permission is limited, respect the limit in the headline, imagery, social promotion, and downloadable versions as well as the article body.
Explain the problem and the scope precisely
Describe what the customer needed and which part your team handled. Name the relevant constraints: an existing platform, a deadline, a content dependency, or a workflow that had to continue operating. Then explain the choices made within that situation.
Distinguish a deliverable from an outcome. Launching a redesigned site is a deliverable. A measured change in qualified inquiries is an outcome that needs a reliable comparison. If other campaigns or operational changes happened at the same time, say so rather than assigning the entire result to one intervention.
Use evidence you can stand behind
For a metric, record the source, period, definition, and any important limitations. For a testimonial, use the customer's actual approved words and preserve the meaning. The FTC's endorsement guidance is a useful reference when customer statements become advertising.
If outcome data is unavailable, focus on the problem solved and the delivered functionality. A clear explanation of a difficult migration or a simpler staff workflow can still be valuable.
Close with what a reader can learn from the project, while acknowledging what was specific to that customer. An honest case study helps people judge fit. It does not need to pretend that one project establishes the result every future customer will receive.