To remember which card to use for purchases, 
when I am not working on earning a welcome bonus.
To help me choose which cards to open based on
 where I spend the most money.

How I USE it

The majority of cards earn a different percentage or points multiplier depending on which category your purchase falls under. To maximize your points and earn the most value with every dollar, you want to be sure to use the card with the highest return. 

You might see a lot of military using the platinum card for every purchase, but it only earns 1 point at most stores. You can earn up to 7 points per dollar on groceries and dinning and well above 10 points per dollar at hotels. Finding the right card to use is the best way to earn points outside of welcome bonuses.