It’s almost impossible to get an upgrade on a full flight, but less busy times means there’s more likely to be vacant premium seats.
If you travel often, get onto the loyalty scheme of your favourite airline. It’s a bonus point for airline staff in giving you a better seat and it could also help you get money off your next trip.
Get there well ahead of time as there are more seat options.
If you win over the check-in staff, they’re more likely to do you a favour.
No one likes inbox spam, but there could be some emails offering free upgrades.
If you’re dressed well, this has been proven to help your chances.