Before we deal with the actual accident itself, we should make sure of the preparations. In Germany, a warning waistcoat and the required first-aid box should not only be in the car when one has to go for an MOT, the latter of course, should not have overshot the expiry date.
Even though border checks are quite rare nowadays, carrying a green insurance card is always a good idea. There are some European countries, who won't allow you to enter without such a card, e.g., Bosnia and Herzegovina. The emergency telephone number 112, is uniform in Europe, regardless of any parallel numbers that the individual countries also have. Indeed, the 112 can sometimes not be reached in parts of some countries, e.g., Italy, Bulgaria and Romania.
In the event of an accident, a digital- or cell-phone camera is worth its weight in gold, particularly if the road concerned has to be cleared quickly. Rather shoot too many pictures than too few. With a camera, the documents from both parties, possible witnesses an number plates can be quickly established. A good idea is also to check the quality of the picture, anything fuzzy or out of focus, is of no use at all.
Be careful when getting out of the car ...
The post-accident care begins already when leaving the vehicle. In this case, particularly if the accident has taken place on a motorway, extreme caution is the order of the day. Even before one tries to help the injured, one should caution the following traffic that there's an accident ahead and put on one's own warning waistcoat.
Take care of the persons first ...
Those involved in the accident, would be wise to say as little as possible and definitely should not sign anything at the scene of the accident, they should quickly grasp where help is needed most urgently, e.g., when a person or persons are injured. In this case, the emergency number 112 (fire-dept.) makes more sense than the 110 (police). Try to give the most accurate information as possible.
Never simply drive past an accident, if you're not sure that your help may be needed. You are, by the way, obliged to give assistance and can be judged by a court of law if you fail to do so (at least in Germany). If rescue teams are already at the scene, then drive past briskly and carefully, otherwise you may simply hinder the helpers and cause a tail-back.
If involved in the accident, only leave the scene when you're sure that everything is cleared up and all the details have been taken. Being accused of a hit-and-run crime, is to be avoided at all costs. A note with your name and address clamped under the windscreen-wiper is not enough, it may be blown away by the wind. Take every suspicion of damage seriously and never accept any form of compensation at the scene of the accident.
By the way, regardless of whether the police appear at the scene of the accident or, in the case of minor damage, they don't, the onus is on you to secure the facts, the police don't do that. If, e.g., they issue an exemplary fine, by no means does that clarify the liability issue in a civil court case.
To the following video it must be said, that as the aggrieved party, one is not obliged to place oneself in the hands of the opposing insurance company. If the damage amounts to more than €1000, in Germany, one can appoint an estimator of one's own choice and is not obliged to have the car examined by the advisory experts from the opposing insurance company. 04/15