We already told you about some advice the College Board book gave about the SAT essay, which to sum up was: thinking is dangerous on the SAT and will get you in trouble.
Here's some more advice, this time from online SAT test prep resources:
You may have qualms or otherwise “sophisticated” thoughts at this point. You may be thinking, “I could argue the ‘agree’ side pretty well, but I’m not sure that I 100 percent believe in the agree side because. . . .” Drop those thoughts.
The examples you choose to support your argument and your development of those examples is a big part of how well you write. But there’s no SAT rule or law that says that the examples you use to support your arguments have to be true. If you’re in a bind, however, remember that you can bend the truth a bit and use your personal knowledge and experience to generate examples that prove your argument.
Forget about trying to write an essay that changes the world. When the SAT says to you, “Here’s 25 minutes, write an essay,” what they’re saying between the lines is: “Write a essay that does exactly what we want.”