Is there a procedure for pick-up and drop-off?

There certainly is. 

Pick up...

Take 4 images on your phone of the vehicle prior to it being shared (front, rear and both sides).

Drop off...

Take 4 images of the vehicle after it has been shared (front, rear and both sides).

Make sure you take any images of any dents, scratches or markings that weren't there previously.

(Its worth also reading the Meeting Up FAQ for more information on the information that you need to have with you when sharing).