By helping you comparison shop, the Internet can you save big bucks when you rent a car. But don’t turn a good deal into a blooper by making these mistakes:

Don’t forget to check the car’s condition when you pick it up. Believe it or not, some companies may try to blame pre-existing dents and scratches on you, so when you pick the car up, check it for imperfections. You don’t have to use to a magnifying glass, but be reasonably thorough. If you find something in excess of normal wear and tear, take a picture of it. Your cell phone camera may end up saving you from being charged for a repair that you wasn’t your fault.

Don’t forget to check offline for a better deal. Even though the Internet is likely to be the best source of the best deals, a local car rental company might be offering a special or might have a cancellation that suits your needs.

Don’t check the terms. Before you sign on the dotted line, make sure you’re getting unlimited mileage. It’s rare, but sometimes the agreement doesn’t require you to return the car with a full tank. If you filled it up, but didn’t have to, that’s money out of your pocket. Most likely, you will make your rental car reservation at a Web site, so that’s the best time to read everything carefully. Be sure to make a copy of the final agreement by printing it. Then review the printout. If you see something you don’t like, you can cancel the reservation.