|Status: This is an official style guideline.|
Das erste Wort sollte groß geschrieben werden. Für den Rest gilt die übliche Groß- und Kleinschreibung.
Capitalize the first word of a title, and stick to the normal German capitalization rules for the rest of the title.
For non-German speakers the main rule of this document in short: Nouns (also "common" nouns, not only proper nouns) and the first word of a sentence/title are capitalized, everything else is not. This is not completely correct, but appropriate most of the time.
In text written in all caps, "ß" is commonly written "SS". When correcting the capitalisation, the usage of "ss" and "ß" should follow standard German orthography (e.g. Rammstein's "WEISSES FLEISCH" should be capitalized as "Weißes Fleisch"). Please note that the use of ß has changed after the 1996 spelling reform (most important: new spelling dass and muss instead of daß and muß, but still ß after long vowels, e.g. groß, and after diphthongs, e.g. weiß).