I've recently started dating a girl who has a fairly aggressive dog.
I have never seen the dog, but from her stories, the dog is pretty
aggressive to strangers, especially guys. I've been reading up on dog
behavior, particularly dominance related, and from what I can gather I
think the dog considers itself the alpha. Its a German Shepard,
something else mix, and about 60 lbs.

I've dealt with my share of dogs, including walking dogs for the aspca
for a bit, but dogs that don't like guys tend to not like me.

I'm going to her place sometime soon, and am going to have to deal
with the dog. I'd like to figure out the best way to deal with this
situation, and certainly anything I really shouldn't do. Here's an
example of a situation I don't want to wind up in.

About a year ago my parents were watching a pair of German Shepards
that belonged to my step-brother, who is a police officer. They were
strictly trained, certainly for defense or some such. One of them
actually bit me in the arm when I followed my Mom into the house
(warning bite I assume, didn't break the skin). For the next few
days, anytime I moved, stood up, whatever, the 2 would run at me
barking. I was even petting the male, and went to stand up, and they
both came at me again. Basically, my guess is that they established
that I was lower in the pack, and felt the need to remind me
constantly. I'm no expert on dog behavior, but I'm guessing it was a
dominance thing. Anyway, I didn't feel the need to expel the energy
or take the risk of trying to change the situation because I was only
going to be there for a few days.

From what this girl has told me about her dog, I think the situation
could be similar. Any suggestions? I've read a lot about how an
owner should try to change an aggressive dog's behavior, but not much
about how a stranger should deal with such a dog.