Use structured entries for numbers and notes for the context behind them.
What belongs in a diary
Keep exercise names, weights and repetitions consistent. Add short notes for equipment changes or information you will need when reviewing the session.
Avoid rewriting history
A missed set or changed exercise should remain visible. Correct data-entry errors, but do not alter actual results to make a plan look completed.
Review one question at a time
Compare a particular lift or setup rather than treating a single workout total as a complete measure of progress.