Capital letters
- Every noun takes a capital, including words turned into nouns: das Lesen, beim Essen, etwas Neues, im Allgemeinen.
- The polite form: Sie, Ihnen, Ihr always with a capital; that's what tells it apart from sie (she, they).
- Small letter: adjectives of nationality (deutsch, schweizerisch — unlike English "German"), but the language as a noun: Ich lerne Deutsch. The adverbs montags, abends, morgen (tomorrow), but heute Abend, der Morgen. And ich is small, unlike "I".
ss or ß?
- ß after a long vowel or a diphthong: die Straße, groß, heißen, der Fuß. ss after a short vowel: der Fluss, muss, essen, dass.
- That's why the spelling changes within one word family: wissen → er weiß; der Fluss → fließen.
- In Switzerland (and Liechtenstein), ß is never used: Strasse, gross. In capitals everywhere: STRASSE.
- das or dass? If you can replace it with dieses or welches, it's das (article or pronoun). Otherwise it's the conjunction dass.
- Without a German keyboard: ä, ö, ü → ae, oe, ue (Mueller).
Commas
Always before a subordinate clause and around a relative clause, before aber, sondern, denn. Usually not before und / oder. Never between subject and verb.
Beim Lesen lerne ich viele neue Wörter.
When I read, I learn lots of new words.
Ich hoffe, dass das Wetter schön bleibt.
I hope the weather stays nice.