Have you been receiving a number of credit card offers lately? You probably have if your credit rating is pretty reasonable. Don't just sign up for the first offer you receive. Take the time to compare credit cards.
Make sure you have enough credit but not too much. Even if the credit is unused it can count against you when you want to buy a new car, refinance your mortgage, or buy a house. The lender thinks that even if the credit isn't used now, you could use it in the future.
Don't get confused by all the bells and whistles. Credit card offers can have different late fees, interest rates, membership fees, annual fees, cash advance fees and separate cash advance interest rates and usage fees. Decide what you will be using the card for and how often, then decide which card is the best for you.
Compare apples to apples when an offer comes in. A lower rate interest or even 0% interest may sound like a great deal, just make sure that after an initial time period the interest rate won't go higher than your current card.
Credit is not the same thing as cash in the bank. Just because you have an unused credit line of several thousand dollars don't think you have to use it. Save your credit for when you need it.
Take the time to compare credit cards and you'll have a good chance of finding the one that's right for you.