Even if we don't emphasize, the verb is often before the subject, because it must be in the second position. Starting the sentence with a time expression, we automatically get: time + V + subject. Morgen fahre ich nach Berlin. One could also say: Ich fahre morgen nach Berlin. But we prefer the one with the time in the first position. So, as soon as the first position is "occupied|" by another word, the subject has to go in the third position. And then, there are many rules for the word order. The most important is that the part of the sentence which belongs to the verb (here: nach Berlin) is usually at the end of the sentence. And in between we got the nice order TeKaMoLo or wawawiwo, which means: 1.time 2. reason 3. how to do something 4. place. Of course, one does not have to have all of them.

In a main clause, the verb must be in second position. There's no fixed place for other parts of the sentence, though there is a "neutral" word order. If the subject is not in first position, it will usually be put after the verb. Examples: Ich gebe dir ein Buch. (neutral) Dir gebe ich ein Buch. (emphasizes "dir") Ein Buch gebe ich dir. (emphasizes "ein Buch")

Gianluca, dai un'occhiata a questo sito; spiega, secondo me in modo incredibilmente chiaro, la costruzione delle frasi in tedesco e tutta la grammatica che c'è dietro. http://venus.unive.it/tinrete/tedescoinrete.it/