You can increase your chances of being selected to take the empty first-class seats without paying First Class Airfares. It happens.
1. Dress smartly. Look professional
2. Be pleasant
3. Fly solo. If you're traveling alone, there is a greater chance of getting an upgrade than if you travel with a friend
4. Get to the airport early. Ask politely for an upgrade as soon as you arrive. Be on their radar early
5. Fly the same airline every time and sign up for any customer loyalty program
6. If flying for a celebration, like your birthday or honeymoon, tell the airline staff when you check-in. They may upgrade you as a present. But don’t lie and make something up!