Having a credit card and using it responsibly is one of the best and fastest ways to build your credit rating. By paying your bills on time, you are improving your credit score, but don't become overstretched--not paying your bills on time will hurt your score. You want to spend with your credit card to build credit, but approaching your credit limit can actually hurt your score, even if you can pay off your balance in a timely manner. It takes time to build a good credit rating, so be patient and avoid opening up credit cards needlessly, as this will probably not improve your credit score.