Smart tricks for instant upgrades.

* Airlines reward loyal customers. Stick to one carrier to score a perk (same goes for hotel chains).

* Know the lingo. "Is the plane full?" is what an amateur asks. "What's the load today?" is the line pros use when looking for an upgrade, says Peter Greenberg, author of The Travel Detective.

* Look like you belong in first class. "I know some gate agents who won't upgrade a person in jeans," says Julia Kostenko, a travel agent in New York.

* Travel on a Wednesday. Midweek means more empty seats in first/business class—hence more opportunities for an upgrade, says Gina Pell, CEO and founder of Splendora ( www.splendora.com), a luxury-travel and shopping website.

* Use a high-end travel agent. Often, they'll add a CIP stamp to your booking record — that stands for "Commercially Important Passenger" and tells the airline you're worthy of an upgrade, says Pell.

* Some airlines (Airtran, America West) let you buy a discounted upgrade on the day of your flight.

* If all else fails, make your own first class, says Pell. Reserve a bulkhead seat or exit row. Stock your carry-on with cashmere socks, earplugs, an eyeshade, facial mist, and a pashmina blanket.

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