The review season checklist
Most people prepare for a performance review in the week before it is due, from memory, under time pressure. That is the worst possible condition for recalling a year of work. Everything below is something you can do now instead.
Write wins down while the details are still fresh
A win recorded the day it happens keeps the specifics: the number, the person you unblocked, what would have gone wrong otherwise. A win recalled eleven months later keeps only the shape of it, and a vague claim is easy for a reviewer to discount. You do not need to write much. One or two sentences with the detail attached beats a paragraph of reconstruction.
Record the outcome, not the task you did
"Refactored the billing service" is a task. "Cut failed payments by removing a retry bug that was costing us renewals" is an outcome. The second one survives being repeated upward by your manager to people who have no idea what the billing service is. Every time you write something down, add the sentence that says what changed because of it.
Check what your manager is actually measured on
Your manager has their own goals, and the work of yours that helps them hit those goals is the work they can argue for most easily. This is not cynicism; it is just knowing which of your contributions translate. Ask directly what their team is being judged on this cycle, then look at your own list and mark the items that connect.
Ask for the review format before the week it is due
Self-review forms differ enormously: some want a narrative, some want examples mapped to a competency rubric, some want peer feedback nominations weeks in advance. Finding out which one you are facing while there is still time to prepare for it is free, and it removes the single most common source of last-minute panic.
Keep evidence, not just claims
For each item on your list, note where the proof lives: the link, the dashboard, the thread, the person who would confirm it. You will almost never need all of it, but the two or three times you do are the times it matters most, and hunting for a link from eight months ago is how a good example gets dropped from a self-review.
Include the work nobody saw
Prevention, mentoring, unblocking, and cleanup all produce no artifact when they succeed, so they vanish from a self-review unless you deliberately put them back in. State them as what did not happen: the outage that did not occur, the escalation that did not repeat, the person who now works independently.