When airlines don't sell all of their first class seats or when the flight is oversold, they'll usually begin upgrading people with loyalty status. It's the same story for hotel loyalty programs. Remember that many airlines and hotels belong to a larger umbrella, and typically you'll score the same benefits from the partners of your preferred airline and hotel, too.
"Do all you can to stay loyal to your preferred airline to build up mileage and reach the top levels of frequent flyer programs," Tom Spagnola, senior vice president of supplier relations at CheapOair, told POPSUGAR. "As a bonus, use a loyalty credit card that helps you earn miles every time you make a purchase. The airlines can see your loyalty to your preferred airline and also the airline alliance that they're a part of."