Make a list of 20 of your recent sales or new clients. The trick is to take 20 in a row - without picking anyone specifically.
Identify what product he bought and how much he paid.
Answer yes or no to the question, "Would you like to add this customer and their sale as a successful case study to your website or product presentation?"
If the answer is no, it's worth thinking about what you're doing wrong in your marketing (targeting, offers) that you're getting those sales.
Describe the story of how the sale was made. Is it a regular customer? Is it a new customer on the recommendation of an old one? A lead from an application form on the website? Why did he decide to buy it? Why did he finally decide? Between what and what did he choose?
After that, take another look at your targeting and offers - can you change them to increase the repeatability of some of these stories?
Make changes based on the results of the analysis, run a new ad campaign, wait for the first results - and do it again.