So get a card while you’re in school, but choose it carefully. Look for the lowest available annual fee and interest rate. And don’t go overboard–one or two major bankcards (Visa, MasterCard, American Express, or Discover) should be enough for now. But be careful with spending. You don’t want to ruin your credit before you can even build it up.

Although your first few credit accounts serve to build and improve your credit history, there typically comes a point when each subsequent credit application can reduce your score. Where that point is, no one knows for sure; all Fair Isaac will say is that it depends on the other information in your file.

That shouldn’t keep you from applying for a car loan if you need a new vehicle, or getting or refinancing a mortgage. But if you already have three or four major bankcards, you should think twice before applying for another one.

You also should resist the urge to apply for those “instant” accounts retail stores are always pushing. Sure, you might save 10 percent on your current purchase, but you could wind up paying more in overall interest if the application lowers your score.