What most naturally follows?

How to enroll in a frequent flier program
Select an airline that offers numerous flights out of your nearest airport.
It's best to use a single airline for most of your flights so you want accrue mileage faster. It also will be easier to redeem miles if there are many flights to choose from.
Look at how many miles you must fly before you can redeem them for a free flight. Choose an airline that doesn't require flying more miles than other airlines.