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.
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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！！！