It's clear in the case of compound nouns, double s should be used e.g. Bundesstraße, but with other words I cannot see a pattern. To me it appears to be used somewhat randomly, e.g.: besser ...
I was taught (several decades ago) to write a capital D for all pronouns such as Du, Dir, Deine, when writing to my German penpals. I am afraid it would look antiquated or very formal these days. Is ...
To my knowledge, German is the only language which capitalize the first letter of each of its nouns. Why is there such a rule? Meines Wissens ist Deutsch die einzige Sprache, in der der erste ...