You will require an EU valid license and International Driver Permit to drive in Portugal. Always carry the vehicle registration documents, third party insurance papers, your passport, driver permit, and license while driving. Make sure that you are carrying the requisite car tools like spare bulbs, wheel, reflective warning triangle, etc. Also, driving is on the right side of the road. You will come across some roads with tolls, so ensure that your rented car has an Emovis tag. This tag will let you pay your motorway toll without stopping at the toll plazas.