How do I plan a trip on europe effeciently [closed]

As a couple of comments mentioned, the big problem will be what is open over Christmas and New Year. Throughout Europe, this is a time of restricted travel options and restricted opening of attractions, restaurants, and hotels booked up months in advance.

The other problem I see, is trying to do too much over a short time. Four cities, with a day of travel between each of them, in just 11 days, won't leave you with much time for sightseeing or for stopping off to see somewhere else on he way. And bad weather (snow/ice) might make travel even slower.

Even so, assuming you are travelling mostly by train or rental car, here are some suggestions on what you could see between cities if you can stretch your plan:

Berlin - Munich: Stop off in Leipzig, Nuremburg and maybe Regensburg.

Munich - Salzburg: Not much to see on the way, but Hitler's Eagle's Nest mountain retreat is south of Salzburg if that's the kind of thing you want to see.

If instead you meant Salisbury, UK: It is a long drive/train from Munich - you would be better off flying to London, then train to Salisbury. But once in London, there is a lot more to see there.

From Salzburg to Paris is a long day by train, or a non-stop 11 hours by car. Once again it is best to fly, but Salzburg's small airport doesn't have a direct flight to Paris, it might be better driving back to the much bigger airport in Munich. If you do go by land, you could stop off in Ulm and Epernay, or go via Switzerland (though in mid-winter mountain passes might be closed so you will be restricted to major highways which tend to stick to the flatter parts of Switzerland).

To be honest though, there is enough to see in either Berlin or Paris to occupy a week or more.