As Abby noted, there is not a one-size-fits-all formula for writing essays for the SAT (or any standardized test, for that matter). That's because this portion of the exam is meant to test your ability to craft a coherent, compelling argument with limited resources in a set amount of time; the focus is on your creativity and knowledge, not a specific format.
Of course, there are elements of the essay you should absolutely be prepared for; these include using appropriate grammar, syntax, spelling, and paragraph structure. The test is concerned, in part, with your command of the English Language in all its elements.
But besides showing the graders that you are a strong writer, this section is also about demonstrating your working knowledge, and your capacity to pull information from your previous academic experiences to drive home an argument. One trick I've found very useful in my own studying was reading a newspaper or magazine for an hour every day in the two to three weeks leading up to the exam. Not only does reading a publication like The Atlantic or The New Yorker help you identify words you may not know (and this will bump your verbal score) but it also provides plenty of great material that you can pull from when deciding what examples you'd like to use in your essay.
I excelled in the Verbal and Written portions of the SAT and GRE and recently scored in the 96th percentile for Verbal, and 98th percentile for Writing in the GRE. I'd be happy to let you in on more tips to help you achieve your maximum score.