Before actually looking at car rental companies, you need to know if you are allowed to drive in the Netherlands. You are allowed to drive a car from the age of 18 but you are only allowed to rent a car from the age of 19. Unfortunately, most companies request a minimum age of 21 with two years of driving experience. For heavier or faster cars, there is a minimum age of 25 with three years of driving experience. This may vary by car category, as heavier or faster cars may require more experience. At the very least you should have held your driving licence for at least one year.
Of course, requirements can differ from company to company and it is important that you check the small print carefully. When you book online, it's easy to miss the fine print on age and nothing is worse than arriving at the counter, only to be told; "sorry, you can't rent a car."
Drivers under the age of 25 may incur a young driver surcharge and the renter and the driver have to be in possession of a valid driving licence.
Driving licenses printed in a non-Roman alphabet (Arabic, Chinese, Japanese, Cyrillic etc) must be complemented by an International driving licence. Do not forget to bring a valid ID card or passport at time of pick up.
Make sure that you check your contract as well, as rental agencies often try to make you pay for items you do not need. Make sure that you make photos of the car when you receive it and if the car has damage, that this is written down somewhere. You do not wish to pay for damage that you did not cause!
All major car rental companies can be found in the Netherlands with offices in major airports and cities.