Numerous previous rentals
Well, taking pictures won't do any harm...but shouldn't be necessary. Do a full walk around in the best light..you can find. If it is dark in the lot at time of pick-up..just drive the vehicle under a light within the lot...to get a better visual. Note anything of concern...scatches, dents, paint chips. Ensure the windshield is not cracked or chipped. However having said that.. I once had a Lot attendant tell me that they are looking for "Fist sized" damage.....little door dings, scratches...not so much. Not worth having the car out of the fleet to fix.
What I will tell you...when picking up your rental vehicle...you want to be your sharpest. This is the time that the ever vigilant rental agent is looking for the weary traveller to take advantage of some of their company's "Deals"
* Never agree to bring the car back "Empty" Just keeping saying 'I will bring the car back Full...I will bring the car back Full" It seems there are stlil some out there that will succumb to one of the rental car company's BIGGEST money makers.
They will charge you for a full tank regardless of how empty you return the vehicle. Difficult to drive around on fumes also.
* Rent the size vehicle you wish to drive. Accept a complimentary upgrade if you wish...never agree to Pay for an upgrade..... It is always per day.. and can really add up. Chances are that they don't even have the class vehicle you reserved and were going to have to give you a complimentary upgrade anyway (Had this happen many many times)