I will be studying in St. Petersburg for about 4 months. Does anyone have advice on how to be able to fit in so I will not be conspicuously American (because I hear this makes one a target for theft)? Any other advice for a long stay in Russia would be welcome as well.

Get a bad complexion, knock some of your front teeth out, and run around with a ratty scarf tied over your head....and get a better source of information.

I would say that acting like an obnoxious tourist makes one a target for theft, not being an American. If you happen to be female, always watch your purse, especially in cafes. Don't flaunt a huge camera around everywhere, keep a close on your money/belongings at all times, wear a money belt hidden somewhere if you are traveling, etc.

Russian girls tend to dress very feminine, over-feminine, bordering you know what in my opinion (tight, tiny, very revealing, always super high heels, lots of make up, very fashion conscious). I dress in slacks, linen shirts, sweaters and low shoes. It is obvious that I am not Russian, but nobody has stolen anything. It is not your looks or fitting in that keeps the theft away. It is luck and being careful.

I think that the previous poster was correct- Russian girls do tend the "dress up" more. Messy pony tails and loose fitting jeans will make you seem different. I think that one of my main keys is my "Russian Face"- not smiling at strangers as they pass on the street, looking almost... sullen. Obviously, Russian people are not as miserable as the casual American observer might think at first glance- but they do see the American "big smile" as fake. Some of my most genuine friends live in Saint Petersburg, and the people will go out of their way for you, once they get to know you a bit. I guess I have done well fitting in, as I have passed for Russian more often than not!
Now to the question of safety... As in any big city, standing out can make you a target. Be careful of the "gypsies", as they are the most persistent and can be menacing (even the children). I watched helplessly as a group of Japanese tourists were surrounded there by some kids. These tourists did stand out, and didn't react well. If you are studying there, I assume you speak Russian-- a few choice phrases can keep any of these kids away.
(In my own defense- I am not heartless- I am a teacher myself. These kids are more than likely using the money to buy drugs. If you feel moved, do what I have done- buy them a sandwich.)
Please feel free to ask if you have any further questions! I love Piter, and will be there in the fall.

No one will ever think you anything but an American unless you throw out all of your clothes and shoes and reoutfit yourself completely in Russian gear. Also - you will have to lose the American (I own the world) walk. And don;t smile very much either.

Frankly - I doubt you could pull it off without help from the CIA.

Katya_NY: I do speak a moderate amount of russian. You said there are choice phrases to keep gypsies and hooligans away. What are these? Thanks!

A well timed "ot-valee" or "von otsuda" (can't type in Cyrillic here!!) usually does the trick! I have to admit, though- as long as you aren't walking around speaking English loudly, carrying an enormous bookbag or fanny pack, you probably will not have to use it. I have, in my 14+ years of visiting Russia, only had to use it 1-2 times. Just treat StPb as any other major city and you'll be fine.

I can't believe that Auntida could have posted such a description of the Russians in St. Petersburg. The people there are among the nost attractive that I saw in Russia 15 years ago. When you get into the interior of Russia, it may be a lot different, but I didn't see many that would fit Auntida's description.

You never can "imitate" another culture unless you live there for years and slip into it naturally. Looking at you they will probably be able to tell anyway unless you are Russian/Slavic ethnically. I would just be street smart and get to know people who can tell you where to go and what safety issues there are over there. I have to in my ecperience agree with Elina and dress sense and if it's not your thing don't copy, be yourself and be alert. I was convinced we would get pickpocketed in Spain and I was just careful, had my old NYC radar on in my head and was fine. Have a wonderful trip.