Having transport of your own makes life a lot easier, especially if you live in a remote area, lugging your shopping around on Greek public transport is not an attractive option.
You may have a car at home and be thinking of driving here and permenantly keeping it in Crete. In this case you need to beware of the importing a car regulations. Which effectively means that if you do bring your car here you will need to import and register it by a regulated procedure.
There is also your driving licence, road tax, car insurance and even buying a car here in Crete that you need to consider.
First assume that everyone else on the road has not passed any driving test and therefore a potential threat to your safety. The highway code as we understand it does not exist, so drive as if you are the only one who knows.
Keep your distance twice the normal from the car in front of you, as anything he does unexpected you have time to react, it also allows the car behind you who is nudging your bumper to overtake into space. Even if there is no space they will attempt to do it.
Normally the Greek way of life is very slow, when a greek gets into hia car, he immediatly turns into a F1 racing car driver. Nothing, in front should be in his way, and however big your car is, his is bigger and you should give way. Its a good idea to practice driving through narrow spaces and reversing into no space against a wall, with this skill you will have a great advantage.
Finally, what is the smallest fraction of time the human mind can register? The time that elapses between the moment the light turns green and the momment the greek behind you leans on his horn.
To be a good driver you need nerves of steel and not suffer from claustophobia, and have lots of patience.