Keep official submissions, payment confirmations, USCIS and State Department notices, and any response receipts in chronological order.
Read the operative instruction
For each record, note what it asks you to do and what it does not decide. Maintain the original notice with any adviser explanation. A personal checklist can help organise the process, but only the relevant official record and its legal meaning can establish the agency action that occurred.
Read the operative instruction rather than the covering message, since the two are frequently written by different people for different purposes and only one of them governs. Keep the actual notices, receipts and instructions as issued, with their dates and reference numbers, rather than an adviser's summary of them. Where an instruction directs a step, note precisely what it requires, by when, and what happens if it is not met.
Maintain a single chronological file so that the sequence is visible, and record for each entry which document it came from. Where something was communicated verbally, write it down and ask for confirmation in writing. A file assembled this way lets anyone joining later establish the position from the documents rather than from an account of them.
Where a notice refers to another document by reference, obtain that document rather than relying on the description, since the operative terms are frequently in the instrument referred to rather than in the notice itself.