Capture the useful shape
A small win becomes useful when it is written clearly. Store the client problem, your action, the result, and why that result matters to a similar buyer.
Do this soon after the proposal is marked won while the details are still specific.
Use proof where it reduces doubt
Proof is strongest when it answers the client's current risk. Put a delivery proof near scope concerns, a communication proof near messy coordination, and a speed proof near deadlines.
Do not paste every proof point into every proposal. Relevance is what makes the snippet persuasive.