If you’re new to travel in southeast Asia, don’t plan on renting your own car to get around. I guess if you stick to the countryside and aren’t planning to drive in any cities you might be okay, but don’t count on it. Even if the country you’re visiting drives on the same side of the road as you’re used to, chances are their driving style is going to freak you out.
My first time in Hanoi I hired a driver. Actually, he saw me eyeing scooters for rent and even though he didn’t speak any English; convinced me to get on the back of his scooter and I toured the city with him for two days. I am forever grateful to him for that gesture as I’m sure it saved me from a terrible fate.
Since this trip I have hired drivers in several other countries where traffic lanes and rules may exist but it appears to me that nobody follows them. This is an orderly four way intersection in the center of Hanoi. Vehicles, pedestrians and motorbikes all go in whatever direction they like, whenever they like. I believe the only rule is that if you occupy the space then somebody else can’t. If you see an opening you just go for it. So if you’re walking around and encounter this sort of traffic, look for your opening and just go for it. So long as you’re not being obviously stupid, the traffic somehow magically flows around you.