Renting a car can leave even the savviest traveler itching to hit the brakes. Rates change often, and fees and taxes can drive your bill 30 percent or more above the base rate. But you'll save money if you take the time to:

Compare. Use Travelocity.com, Expedia.com, or similar sites to search for rentals. Take the three best deals you find and go to the rental companies' Web sites or call their toll-free numbers to ask for a better rate. Then call the local office of the company with the lowest price, and see if the agent there will beat it.

Forget labels. Some rental outfits aren't name brands but they might offer good deals. Go to CarRentalExpress.com, CarRentals.com, or similar sites for the names of such agencies. Consider Hotwire.com, which offers deals without revealing the name of the rental agency until you've booked.

Ask for discounts. Most agencies give them to members of AAA, AARP, or warehouse clubs.

Be on time. If you show up after your scheduled return, you could pay for an extra day. (The grace period is often just 30 minutes.)

Avoid the airport. It's often cheaper to rent from an off-site office. Some rental companies, such as Enterprise, will pick you up and drop you off at no charge.

Book small. If that teeny Geo isn't available on time, you could well be bumped up to something spacious for the same price.

Say no to insurance. Most private auto-insurance policies cover rental cars as long as the person who signs the agreement drives.

Inspect the car. Make sure the rental rep sees any nick or scratch before you leave and notes them on the agreement.

Gas up before returning. A rental-car agency might charge two to three times what you'd pay at the pump. Note nearby gas stations as you're leaving the rental lot.