Did you know you can give a rental car company your airline frequent flier number to earn extra points? The same works for hotels! It’s called “double dipping” or “crossover rewards”. Next time you travel, ask if there is a benefit to giving the hotel, airline, or rental car company an additional rewards number to record in their system. Chances are you can earn more points!
Here’s some more info on the current programs that allow you to “double dip”: https://thepointsguy.com/2016/05/maximizing-crossover-rewards/