Flying in first class may sound like a once-in-a-lifetime luxury, but it’s more attainable than many travelers realize.

Savvy travelers use points, upgrades, and flexible planning to enjoy first class flights without paying full ticket prices.

First-class fliers have a code. It’s subtle and usually comes with a glass of champagne. If you want fit in before you fall flat in a sea of stares, learn the unspoken rules—lest you mistake the amuse ...