Register with your airline's frequent flyers program, if you haven't done so already. In addition to the usual benefits of such programs, some airlines also allow members to receive complimentary lounge access or access a more exclusive lounge after a certain number of qualifying flights.
Book a flight with that airline. Make sure to book it in the appropriate class, according to the lounge access policies you previously read. For example, if your airlines restricts lounge access to business or first class travelers, book either a business class seat or a first class one.
Show your boarding pass to the airline staff member standing outside the lounge.
Call your airline and check if they allow passengers to buy one-day lounge passes. Some airlines sell such passes to passengers who would not normally be eligible for free lounge access.
Buy a one-day pass either through your airline's call center or at its service counter at the airport.
Show your one-day access pass to the airline staff member standing outside the lounge.
