Well, here I am, 30 days into the Vegan Pact I made with some friends. Being vegan in Germany isn't the easiest thing ever, but then again, it's not the hardest thing, either. I would say that it takes some planning and thought, and I would rate it as a bit more difficult than it is to do in the US. I'll discuss some considerations.
Being vegan at home is the easiest place to do so. Once you have some staples of vegan cooking, it's reasonably easy to whip up something. I am a huge fan of stockpiling vegan cooking staples to throw together quickly. I will also admit that I'm naughty when I'm a vegan: I don't always buy fresh fruits and vegetables so I turn to dried, canned and frozen goods to take me through the busy times (which is mostly all the time for me).
At a Friend's House
Oh boy, this can get awkward. It's always such a kindness when a friend invites you over for dinner and who wants to hurt someone else's feelings by saying that you can't eat something she cooked for you?
There are several different approaches to take with this. First of all, let your friend know that you appreciate the invitation. Explain that you're vegan and you do have some dietary restrictions; would it be possible to accommodate them? Elaborate on what you can/can't eat as not everyone understands what goes along with being vegan. Offer to bring something (at least you'll have a "safe" thing to eat then). Perhaps you can eat the side dishes? Be diplomatic and be careful with your friend's feelings. After all, she probably just wants to spend a nice evening together and here you're giving her a list of what you can't/can't eat!
At the Restaurant
I have found that being vegan in a traditional German restaurant can be somewhat difficult. Much of German food focuses on meat and potatoes. The potatoes might include some sort of meat (such as Speck) and/or might be covered in some sort of cheese or cream sauce. Even the salads tend to have dairy in the form of yogurt or cream dressings.
It's not impossible to eat vegan at most German restaurants, but you'll have to think carefully and there's a strong likelihood that you'll end up with a green salad topped with some sort of vinegar and oil dressing. Perhaps a dish can be made in a vegan fashion? It never hurts to ask. If that fails, check out the side dishes and see if a combination of those works.
That's not my favorite dinner, so I like to take a different route for dining out in Germany: I try to visit ethnic restaurants or vegetarian/vegan restaurants. For ethnic foods, I love Middle Eastern, Mediterranean, and Mexican restaurants. It's easy enough to find vegetarian and vegan foods there. Even better yet is to visit a vegetarian and vegan restaurant. They're not super common but they are out there.