This article is a great breakdown of the important elements of an effective case study!
A pitfall I see all too often is using a lack of quantifiable results as an excuse to not publish a case study. It’s important to remember that reporting results is optional. You can always edit in these details later, especially if you are waiting on a response from your client.
Few people are showing their work and even fewer are telling the story behind their projects. Case studies — whether they include quantifiable results or not — will set you apart as a designer so add them to your portfolio right away!