Out of curiosity, which leader are you? Frederick or Bismarck?
Germany is my favourite civ (and, IMHO, one of the better civs - terrible Unique Unit and Building, but excellent leaders), but, I'm gonna be real with you, they're not the best for early game rushes. Frederick is one of the best "builder" leaders in the game and if you want to maximize him, peaceful development is the key. Bismarck is a bit more flexible, but he, too, leans slightly more towards empire-building than aggressive expansion. You can certainly pull it off with either of them (preferably Bismarck, though) if you're dead-set on doing an early rush with Germany, but their strength lies elsewhere.
I'd recommend a different civ for early rushes. Conventional wisdom says Rome but I'm going to suggest against that - Praetorians are great units, but you don't want to become dependant on them. It's easy to clean up with Praets at low levels and then discover that you can't really play as anyone else. Hatshepsut of the Egyptians might be a good choice. Solid traits for going to war, a great UU, UB is niche but whatever.
Another possibility is Boudica of the Celts. Their UU and UB are both pretty... underwhelming. But she's got great traits for warfare and dealing with a crappy UU will teach you to not become dependent on them.
(Note: Crappy is relative. The Gallic Warrior, for example, is still an improvement over the Swordsman, it's just not quite as big of an improvement as, say, the Praetorian is)