Get a complimentary upgrade to first or business class

Unless you purchase an upgrade or use frequent-flier miles, there are no guarantees you'll receive one. Still, there are things you can do to increase the likelihood that an airline will bestow one on you:

Some carriers allow you to pay for an upgrade with a combination of cash and frequent-flier miles. To inquire about such policies and about special promotions, call the frequent-flier reservations desk.

If your flight is full and your itinerary flexible, consider agreeing to be bumped should the airline ask for volunteers. Hang out near the gate agents so that if there's a favor to be given, they'll think of you first. If the flight is oversold in coach, the agents not only have the option of putting you on the next flight but of bumping you up a class.

This is a good possibility if the next flight is oversold and the agents are having trouble getting passengers to give up their seats. Chances of getting upgraded are better, however, if you're traveling alone (two or more people are more difficult to accommodate).

You can try trotting out a tale of woe (illness, exhaustion, missed connections, or delays) but skip the melodrama. Your misfortune won't be anything new to airline personnel, and the only thing that will make your troubles noteworthy is the grace with which you handle them. Supervisors have more leeway in changing seating assignments, so look for agents with seniority, which is often indicated by a special pin or a lapel flower.

Remember that gate agents can be under a lot of stress, so good manners go a long way, as does a smile. Never be demanding. Dressing well doesn't hurt, either.