Follow this simple checklist to make sure you do not affect your eligibility for compensation:
Continue with the check-in, security, and boarding process as normal. Even if you know your flight is delayed, make sure you arrive at the departure gate on time.
Keep proof of any expenses you incur to make your wait more comfortable. This includes receipts for food, drinks, phone calls, or, in the case of longer delays, overnight accommodation.
Ask airline staff whether they can provide assistance straight away. They may be able to offer refreshment vouchers or access to facilities that are not usually included.