Is it difficult to find you way to the dollar car rental facility located outside the terminal at AIA
(Athens airport)
Once you are in the public area you can follow the "Car Rental" signs.
You can also ask Dollar how to find their office.
I didn't find the airport confusing. It's not as big as many airports.
A word of warning/advice: If you are planning to drive into Central Athens be prepared for a lot of confusion and one-way streets. You don't need a car there. There are lots of taxis and buses, as well as the Metro system.