This topic is turning into a public service thread. Allow your crazy Uncle Bob to make a few contributions...
When you are in London, trust your driver. He is an expert in how to scotch up and throw the vehicle you are riding in, into something like either a 480 or 960 degree spin (left or right--sometimes both) in order not to slam into the double-decker tourist bus that has either gotten caught in high power and telephone lines and/or has tipped over and spilled Americans all over the place.
If you are in downtown Paris and need to cross the street, move with the herd. That is the only way to cross a downtown street in Paris and live to see the other side. Try to stay in the middle of the pack. It is the safest place for you. French drivers will never attack the herd as a whole. Even though they have superior advantage, they realize that direct, forceful attack against such a large group might inadvertently result in some personal injury to themselves. So when the herd moves, they stop, lay back, churn out hydrocarbons and wait for the central portion to pass so they can then pick off all the young, old, sick and weak stragglers.
If you are in Athens and decide you would like to take an excursion though the local country side, forget about driving altogether. The Greek people are universally humane and will restrain you with force if necessary rather than see you snuff your own life out prematurely behind the wheel of an automobile in Greece. What they will allow you to do is take a "crash course" in Greek highway navigation. It is a complex thing that involves knowing way more than just how to operate a motor vehicle. They will usually start you out in a position I can only describe to other Americans as "riding shotgun".
Gaining mastery of that position is essential if you wish to become the friends of Greeks in any significant ways. Never fear, they will provide you with an assortment of tools to designed to accelerate your learning experience. That usually involves at least a hair-raising car ride that would make "Mad Max" soil his trousers and a sack full of empty wine bottles, empty food cans, cat litter, cats, rancid meat, rotten tomatoes and eggplant, perhaps a busted mandolin or two and other things that cannot be mentioned here that you, as "shotgun" are expected to hurl at other motorists when needed. Notice I said, "when", not "if".
Trust me, they'll provide you with cues and teach you all you need to know about it. Once you get it under your belt, it's great fun. I realize this may sound a bit far out there, but in my opinion, you really haven't lived until you've seen what a fifteen pound leg of stinking mutton can do to the top of a car or one of its windows at highway speed.
The old saying is true, "Travel broadens one."