Relax and get a good night's sleep prior to taking the PSAT. Also, eat breakfast prior to the test to give yourself mental fuel.
Guess in an educated manner on test responses. It is more advantageous to make an educated guess especially on the verbal questions than to leave the questions blank and not select a response.
Try to predict the responses and then select which answer most closely fits your prediction on the Critical Reading/Sentence Completion section. On the Critical Reading/Reading Comprehension section, read the passage looking for the main ideas and start with questions that refer to specific lines in the paragraph.
Avoid awkward or overly complicated responses in the Writing/Multiple Choice portion of the PSAT. Think of the simplest ways to express an idea when responding.
Substitute numbers for variables when you get stuck on the Math/Multiple Choice questions. Even try to insert some of the provided multiple choice responses, but use the middle value response first then try the response higher or lower depending on what answer you get in the initial trial and error.
Respond with only positive numbers greater than zero for the Math/Grid questions.
Purchase a study guide at online bookstores or suppliers to practice these tips several weeks, even months, prior to taking the test. Do study problems before the PSAT to become familiar with the format.