Send The Praise Up
Give credit where it changes something, not just where it is heard.
Telling someone they did well is kind. Telling the person who decides their future that they did well is materially different, and takes the same two minutes.
Praise given directly makes someone feel good for an afternoon. The same praise sent to their manager becomes evidence in a conversation they will never be in the room for. It costs you nothing, it is almost never done, and it is remembered for years by people who found out it happened.
Be specific about what they did
Not great to work with. The specific decision, and what it changed. Vague praise is unusable as evidence.
Send it to whoever decides about them
Their manager, the client, whoever writes the review. Directly, in writing, so it can be forwarded.
Decide separately whether to tell them
Sending it and telling them are two different choices. Telling them is partly for you, and that is fine as long as you are honest with yourself about it rather than calling it pure generosity.
Do it when it happens
Weeks later it reads as a favour being done. Immediately it reads as true.
Go deeper
What the paid version adds to this one.
The wording that makes praise usable in a performance review
How to do this for someone outside your organisation
When public praise backfires, and how to spot it in advance
Real examples across six situations