I usually look at the aisle or row #, but I will still forget which entrance I've used, so that I wind up wheeling a cart all over the parking lot, looking like a bag lady.

Also, I often take Mia-Mimi with me, so I just look for a car with a dog in the driver's seat. (This does not prevent me from using the wrong exit, though.)

Dogs and nature abhor a vacuum.
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