Ok, first
1) Take some deep slow breaths.
2) Realize you know more than you think you know.
3) Read the questions carefully. Make sure you understand the question. Why? Because when I took the SAT, the booklet/info said that 60% of the most common errors were due to MISreading the questions.
4) As @
exexec wrote--try to think of the questions as games or puzzles. You are MEANT to solve them, just like many, many MILLIONS of people before you.
You can do it.