Consider what mass transit and ride share options are available
If trying to cover a lot of ground and see a variety of sights, you will probably want the convenience of having your own car.
Costs can also be a factor. Sometimes it is cheaper to rent a car to get to and from your destination than ride share or taxis.
Loyalty programs can have advantages for rates and efficiency – often getting to skip past the rental counter and go straight to the car
Cars may also be cheaper through 3rd party booking sites like Orbitz, Priceline & Expedia
Prices can fluctuate so it is worthwhile to look frequently in case a better deal is now available. Most reservations can be cancelled ahead of time with no penalty so you may decide to rebook a cheaper rate or to upgrade to a larger car class.
Never pay full price – look for coupons (like in the Entertainment book)
Pay attention to what kind of deposit the rental car company expects – this can vary greatly when you travel global
Research the baggage space to know you have enough space
Smaller cars generally work better in Europe
Check the car before you leave the lot
Take picture of any damage on the car before you leave the lot
Don’t sign a damage form before looking the car over
Adjust your seat, mirrors, etc. before you leave the rental lot
The gas gauge tells you which side to pump the gas