Renting a car should be easy, but it can also be unexpectedly expensive. If you want to see how bad things can get, look at Dollar Rent A Car, which is facing two federal law suits and investigation by Florida’s Attorney General for alleged frequent use of aggressive and deceptive sales tactics to heavily pad bills.

Most rental experiences aren’t like this. However, any time you pick up a car for short-term use, you’re at risk of having to spend more than you should. Here are 13 ways to beat the game and keep more money in your pocket.

Carefully read the printed agreement

Do you know what the mileage limits are per day? How much gas was officially in the tank? The rate you’re actually paying and amount of insurance you’ve agreed to? You don’t know until you’ve read the final agreement. There are some devious salespeople who will pad their quotas toward a bonus with extras you might not be aware of. Or someone might simply make a mistake while running around trying to do half a dozen things at the same time and click the wrong box on the screen. Once you’ve signed and taken the car out, you’re on the hook for what’s on the paper, so read it before you go.

Don’t say yes too quickly to insurance

The insurance plans of the rental agencies are massive margin builders. Getting coverage through them is ridiculously expensive. Most drivers, at least in the U.S., are covered by their own insurance when renting a car. Even if you don’t own a car, there are non-owner policies available from some insurance companies that might make sense if you frequently rent cars.

But don’t say no automatically, either. Some rental companies add additional fees, including charges for lost opportunities to rent the vehicle, if there is damage to a car. Do your homework ahead of time and be sure the insurance you do have will cover these additional amounts. If not, and if you get into an accident, you could end up paying more for these add-on fees than the extra insurance would have cost.

Use the right credit card

Collision and theft insurance may come with a credit card, but card companies differ in what they offer. Some have primary coverage, which means you don’t have to report the accident to your insurance company and see your rate go up. Others have secondary supplementary insurance that may, or may not, cover towing, deductibles, and or the administrative fees mentioned above that can add up. Check your card’s policies ahead of time.

Take pictures of the car in good light

You want any — any — problems with the condition of the car clearly noted. Certainly they should be documented on the rental agreement, but also take photos, both when you pick up the car and when you drop it off. Have hard evidence of the condition so that, if the rental agency claims you were responsible for damage, you can show that you weren’t.

One caveat: Don’t drop the car off after hours if you can possible avoid it. You’re generally responsible for the car until it is officially checked back in. If damage happens, you can end up on the hook for it.

Skip the airport rental when possible

Airport rentals are particularly expensive because a company can get you to pay through the nose for convenience. Instead, see if there are any rental locations within a commute from the airport, whether mass transit or cab ride into a city or a hotel that has a rental desk. The difference in rates can be astronomical.

Location can be particularly important when you rent internationally. For example, you might find that the rental or insurance rates on one side of a national border are much lower than if you were on the other side. It takes research, but doing a bit of work up front can save you a lode of money.

Book the cheapest car class

One of my favorite techniques is to go online and book the cheapest class car listed. When you get to the rental agency, if the type isn’t available, chances are good that you can get something better for the same price.

Of course, the cheapest car is one that you don’t rent. See if there are enough transit options, and time in your schedule, to avoid getting a car at all. Or look at an hourly car share rental so you book a ride for only as long as you need it.

Look for discounts

Whether you’re a member of AAA, have special rental rates through a professional association, or check online for coupons, look for discounts that you can apply to the rental period.

Keep checking for lower prices

Many people make a reservation and then don’t think about it again until they pick up the car. But prices fluctuate and different rental companies might have a relative deal. Keep checking until shortly before you’ll need the car to see if rates change in your favor.

Look at the total cost

You may see or hear quotes for rental rates. Also look to see if they include taxes, fees, and other things that jack up the price. Always compare companies and cars on a total cost basis — and don’t forget that smaller cars or hybrids may make up a lot of expense by using less gas.

Use the frequent renter and corporate programs

If you don’t have frequent renter cards for the companies you most often use, get them. Eventually you’ll get some free driving time. Also, being an entrepreneur, ask about what programs a company has for corporate users.

Unlimited mileage versus caps

You may find a strong inclination to opt for unlimited mileage, particularly if you’ll be driving a fair amount. Do yourself a favor and calculate how much you’re really likely to drive. There may be times when unlimited makes perfect sense, and yet, under the right conditions, the total limited mileage over the days you need the car may be more than enough you need. It takes some calculating, but can save money.

Fill the tank yourself

The most expensive way to get gasoline is to pay the refill charges the rental agency wants. Instead, scope out where you will return the car and find some local filling stations so you can top things off yourself.

Know the grace period and be timely

Some rental companies will hit you for a significant additional charge — maybe a half or whole day — if you come back after the grace period. Since you’ve now read the rental agreement, you’ll know what it is and stick fast to it. Or at least ask someone on the counter. No sense in saving all sorts of money only to blow it because you were help up in a line at a chain coffee store.