Do a lot of practice tests. Tons of free tests are available on the internet.
Make sure you get a good score in practice tests.
Listen to any American news channel/Discovery channel (it will help in listening section). Read American news from washingtonpost.com, nytimes.com, etc.
Be Cool and be comfortable with your seat.
Listen properly in the Listening section. Check all four options before answering.
You will probably find reading section easy but be careful and avoid making silly mistakes.
Again first 10 questions are important. Take your time and do not hurry!
For Listening section use TOEFL CD from ETS. That is the best material available and is a must for practice. You would see the same type of screen (UI), and you will feel comfortable after using the CD.
Answer all questions in each section. There is no negative marking (penalty) for unanswered questions. So in last 2 minutes just guess all remaining questions.
Again You can send your score free to four universities so be prepared for Universities!