I've driven in Germany quite a bit and a few things have caught me out in the past.
If you're driving in town and approaching an unmarked crossroads, you must give way to traffic coming from the right, even if you appear to be on the main road. If you see the below sign on the road you are driving on at the junction then you have priority...
Further explained here...
https://routetogermany.com/drivingingermany/right-of-way
It's illegal to park on the wrong side of the road facing the traffic. If you see a space on the other side of the road you must do a U-turn and come back the other way.
Never wave at someone to acknowledge them giving way to you, they'll think you're a weirdo. And especially don't flash your lights at them or you'll cause an international incident. That action is reserved for emergencies.
Also the roads tend not to have cat's eyes which I find makes driving at night or in bad weather more difficult.
And finally, from personal experience, be careful if you're driving a hire car with French plates on the autobahn, German truckers will see you as fair game to ram off the road