Interest rates

• Credit card companies offering free air miles often have higher interest rates. If you do not pay off your entire balance monthly, this might not be the best option for you.
  
  

Spending habits

• In addition to considering how often you will use your credit card, review your spending habits and purchases. Some credit card companies offer air miles based on spending totals. Others only offer air miles when certain products are purchased.
  
  

Flying freedom

• Some credit card companies offer air miles only redeemable with certain airlines. If you prefer a certain airline for traveling, find out whether it will be available before applying for the card.