1. Know your grammar
No matter how you slice it, you have to know your grammar to do well on the writing section. But don’t think reading a mere section on parallelism or subject-verb agreement is going to make you an expert at it—or know when it is being tested on the exam. You’ll have to do practice exercises in books that focus on grammar. We have many helpful lesson videos that break down the grammatical concepts. Also, our blog has many such lessons (when in doubt, just enter into Google “Magoosh SAT (name of grammar thing you want to learn)”.
2. Know the test
No matter how much grammar review you do, if you are not used to the format of the new test and some of the question types, you’ll be thrown for a loop. Make sure to do plenty of practice in the College Board book to get a feel for the test. You’ll find that some questions are straightforward grammar questions but that others require you to add, delete, or keep sentences; choose which sentence makes for the best topic sentence; and choose the best placement of a sentence (or even paragraph!).
3. Know how to identify the component parts of sentences
Something you can do when you are not studying grammar is to apply what you’ve learned. When you are reading a magazine article or even an advertisement at a bus stop, analyze the grammar. In the case of the magazine, notice how the writer uses subordinate clauses and proper (hopefully!) use of subject-verb agreement and other such grammar 101 concepts. As for the ad, you might even spot some grammar errors.
The point is you are fine-tuning your “grammar brain”. That way, it’ll be a lot easier to turn on test day.