The credit card companies do not offer 0% interest forever. These are just introductory offers, designed to entice you to get a new card. Before signing up, find out how long the 0% interest will last, and what the interest will be after the introductory period.
Watch out for penalty rates
Buried in the fine print will be a passage saying that if you are late on your payments, the company can jack your interest up dramatically, sometimes as high as 30%! Don’t sign up for a card like this unless you are confident you will be able to make your minimum payments on time.
Some companies are even saying that if you default or are late on another bill, they will raise your rate on theirs. This seems very unfair, but it is going on, so beware.
The two-tier interest system
Often, when you get an introductory 0% rate for balance transfers, there will be a higher interest rate for new purchases. When you make payments, the company will apply your payments first to the 0% rate loan. That means that your payments are not being applied toward the higher-interest new purchases, and you won’t even touch that balance until your balance transfer is completely paid off. The best thing to do is to make your purchases using a different card.