Here I list several strategies that can help you curb careless mistakes during the SAT test:

• Read Carefully: Read the question very carefully and read it several times. On the difficult problems, you will not grasp the entire question on one reading. You may have to read it two or three times, or more. In general, harder questions require several readings.
• Stay organized: Do all of your scratch work in a systematic manner. Write in the blank area in the test booklet.
• Write legibly: Your work should be clear enough that you can read your own handwriting. This is helpful in situations when you end up with an answer that is not in one of the answer choices. This often happens when one makes a careless mistake. To spot your mistake it helps if your work is written in a clear and legible manner.
• Don’t use the Calculator: I know a lot of students are completely reliant on the calculator, and many people would disagree with me when I suggest not using the calculator. All of the SAT math questions are written in a way that they can be solved without the use of calculator, and on many questions it might be to your advantage not to use the calculator. The problem with doing your work on the calculator is that you cannot go back to check your steps if you made a mistake. In contrast, it is a lot easier to spot a mistake if you have the steps written in your test booklet.
• Redraw diagrams: On the SAT one does not need to redraw things, but I find redrawing helps me digest the problem and also help me see the solution.
• Slow Down: Don’t rush off to attack the problem immediately and don’t change the problem to what you think it is asking, be careful about that temptation.
• Recognize the Difficulty Level of a Question: Look at the Official SAT tests and recognize where the difficult questions are, generally at the end of each subsection. Keep an eye on the medium level questions where you are likely to trip on misreading the question. The easy/medium questions rely more on how the question is phrased, whereas the harder questions test advanced concepts and one is less likely to trip on verbiage.
• Reread the question at the end: Once you have completed the problem, reread the question to make sure you are answering what the question is asking for. For example, if you defined a variable $x$ to solve the problem, check to make sure the question is not asking for the value of $x-2$.