When turning left or right crossing the street, be especially careful as turning signals in Costa Rica often signify “it’s safe to pass”, which can result in catastrophic situations as they may just crash full on into your car while you are trying to take the turn! If you need to turn and cross the street while there are cars or trucks behind you, simple halt at the side of the street until the other cars have passed, then take the turn.
In general, we recommend renting a 4WD drive in Costa Rica. Do not try to drive on 4WD roads with 2WD vehicles. There is nothing adventurous about it but plainly dangerous. When you go uphill with a 4WD, make sure your wheels are locked. Most cars have buttons to lock wheels automatically but other cars will need manual locking. When you are going downhill, make sure to unlock your wheels.