How Should I Choose an Air Miles Card?

Photo: Kevin Dooley, Flickr

So, you want to sign up for an air miles credit card. That's an excellent idea if you travel frequently, or hope to. By using such a card, you can rack up points that will deliver free air tickets, free nights at hotels, free or discounted vacations, and more.

The way these cards generally work is that as you pay for things with the card, and for each dollar you spend, you earn a certain number of points, or "miles," as travel-related rewards cards refer to them (points and miles are essentially the same; "miles" do not translate to actual air miles). The number of points you earn for each dollar spent varies based on the card and where you spend the money. When you want to redeem points or miles, you can use them to purchase plane tickets, hotel rooms, and often many other items from various retailers. Many points programs let you transfer points to other programs, where their purchasing power can vary.Other programs are more fixed, such as Southwest's Rapid Rewards, where you accumulate points that are meant to be used for Southwest airfares.

As with any credit card, you want to find one with low interest rates and favorable terms and fees. Below are six things you should consider as you shop for an air miles card.

1. Do you want to stick to one airline?Think about which companies you frequent for travel and lodging. A general travel-oriented credit card can serve you well, but if you fly a lot and mostly on one particular airline, or if you like to stay at a certain hotel chain, then look into those companies' travel card offerings. The major credit card companies' general travel-oriented cards are sometimes the best bet, with ties to and discounts on all kinds of services, including a wide variety of airlines, hotels, car-rental companies, restaurants, and more.

2. Is there a sign-up bonus?As you shop around, look for hefty bonuses that various cards offer to new customers. A bonus of 20,000 points or miles is great (points and miles are essentially the same thing; travel-related cards use the term "miles"), but know that if you look around, or are willing to wait, you might be able to grab 40,000, 50,000 or possibly even 100,000 points, or miles. That can be worth several free flights or hotel nights. Check the fine print to see how much you need to spend on the card in order to get the points, and be sure it's manageable.

Photo: Sean MacEntee, Flickr

As an example, theCapital One Venture Rewards Credit Card was recently offering 40,000 miles to new cardholders who spend $3,000 in the first three months. That's worth $400 in travel costs. Note that all miles are not equal. On some cards, the miles' value is fixed, so that, say, 10,000 points is worth $145 in airfare. ThePointsGuy.com breaks down various cards' 2014 mile values in a tablefor easy comparison.

3. What other perks come with card membership?Consider the benefits offered by cards you're considering, too. Some cards, for example, will enhance your air travel via priority boarding, free checked bags, access to airport lounges, occasional upgraded seats, and more. Some cards will even offer travel-planning services, booking services, and travel insurance, among other things.

4. Can I get more with a card that charges an annual fee?Don't automatically dismiss cards that charge annual fees. Some such cards offer a higher level of benefits that might be well worth the fee. For example, the Gold Delta SkyMiles credit card, which recently charged no annual fee in the first year and then $95 per year after that, grants you, among other perks, one free checked bag when you fly. If you travel a fair amount, that perk alone can be well worth the annual fee, as it costs $25 to check your first bag on Delta.

5. What are the currency conversion fees?Check whether cards of interest charge you anything when you use your card abroad if you plan to travel outside the U.S. Some charge as much as 3%, while others waive such fees.

6. When will points/miles expire?Glean all the details you can about any card you're considering. Find out, for example, when or if accumulated points and miles will expire. When you occasionally receive a fine-print notice in the mail regarding your card, read it, as it may explain a change in terms. If the change is bad (higher interest rates, higher fees, faster point expiration, or the like), you might shop for a better card.

One card, two cardsDon't assume that only one card will serve you best. Think through your spending patterns and preferences. You might find that you'd do best with one airline card for free miles and discounted tickets, as well as a general travel card or a hotel-chain card. Don't spread yourself too thin, though, or it will be hard to rack up a lot of points on any one card.

The article How Should I Choose an Air Miles Card? originally appeared on Fool.com.

Selena Maranjian owns shares of American Express and JPMorgan Chase. The Motley Fool recommends American Express. The Motley Fool owns shares of Capital One Financial. and JPMorgan Chase. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.