Take the SAT exam practice tests. Study for the PSAT by using the same study materials and strategies as for the SAT.
Use test-taking strategies, for example, do not leave any answer blank. To ensure this happens, when you near the last 5 minutes of any section, jump to the last question on that section and begin filling on bubbles on the answer sheet, stopping 3 or 4 from the one you left off from. What bubble to fill-in? One of the strategies is to DECIDE right now which bubble will be your, "I have no clue" answer bubble. (Choose bubble 1, 2, 3, or 4. Never the last, 5th bubble.) Since answers are mostly evenly distributed throughout the test, always choosing the (?) bubble ensures that you'll get 25% of those 'I have no clue' answers correct.
Take the SAT practice tests under test-taking conditions--no distractions. No cell phone. No getting up from the cair except for ONE 5 minute break sometime in the middle.
After taking the practice test, wait a few hours or the next day, and check your answers. but do this strategically! Since you've determined which bubbled answer will always be your "I have no clue" bubble, then when checking your answers, if that is not the bubble you chose, then you must have made a conscious decision to choose that answer.
Have no idea what I just said? EXP: I chose bubbe 2 to always be my guessing bubble. I don't have to think about it because I always use bubble 2 regardless of taking the ACT or SAT or PSAT. Same bubble all of the time when I have to guess. When I'm checking my answers, if my wrong answer was bubble 1, 3, or 4, I must have genuinely thought that was the correct answer, otherwise, I would have filled in bubble 2. That tells me that I REALLY have no idea what I'm doing on that question.
But what if I chose bubble 2 and got it wrong? Then you have to decide if you actually guessed, or if you thought it was correct.
Start a notebook for questions or concepts you got wrong. Find out the correct answer and why. This is what you should study from.