Congratulations on the opportunity you got!  I am a jobseeker too, so not experienced.  But I think the book other jms recommended "Nail the interview" is a good one.  Good luck!

Wear dark color suits with white or light color shirt (gentlemen need tie).

Practice questions and anwsers with friends.

If you are not too comfortable with your oral English, prepare your research or work in handouts and make copies for the interviewers. Try to pay attention to the interviewers and answer their questions. Ask them questions related to the company, the position or themselves.

When I was looking for my first job, I did not get an offer until my 3rd or 4th onsite interview. (But I did get good practice from the first few interviews.)  After that I always get offer if I choose to go to interview. So practice, practice and practice with your friends.

Good luck.

Wear dark color suits with white or light color shirt (gentlemen need tie).

Practice questions and anwsers with friends.

If
you are not too comfortable with your oral English, prepare your
research or work in handouts and make copies for the interviewers. Try
to pay attention to the interviewers and answer their questions. Ask
them questions related to the company, the position or themselves.

When
I was looking for my first job, I did not get an offer until my 3rd or
4th onsite interview. (But I did get good practice from the first few
interviews.)  After that I always get offer  if I choose to go to
interview. So practice, practice and practice with your friends.

Good luck.
------------------------------
these are very good advice
口语不好没关系，慢慢说，把话说清楚说利索就行。
尽量放松，一幅confident的样子进去
加油！！！

What is your major?  Are there lots of foreigners in the filed, in the company, in the department?  Not all jobs require very high communication skills.  You have studied in US.  You have successfully pasted lots of tests.  Be proud of yourself.  Show your confidence, and show enthusium during the interview.  Do your research about the company, and prepare for questions that you would like to ask.

mm你是啥专业？楼上的mm说得对，不同的专业不一样啊。不过如果你觉得口语不够非常strong,建议找人帮你一起练习，如果录像下来，更晓得自己的缺点在哪里。学校的mock interview也可以帮你的忙

mm莫担心，俺们b-school以前学德语，俄语，日语的mm全都找到工作的