Everyone makes mistakes when preparing for an exam, but the way you use or don't use this information makes the difference between a great outcome or a less satisfying one. If you aren't already familiar with what an error log is, I recommend reading this article about error logs. This is an effective way to categorize your mistakes and have data to analyze.
This article will focus on how to use that information to learn from your mistakes by presenting different scenarios.
All of my mistakes seem to be random, without a pattern.
You need to look deeper and decide what might be causing mistakes. If your mistakes seem to be random, it might be due to something outside the material, like timing or overall discomfort with material, rather than specific topics. It also could be that you have not yet mastered the tricky way that questions are often written and studying the test format a little more would unlock the key to some of these mistakes. Even though you've just done some serious self-analysis, devote a little more time to thinking of non-content factors!
I keep making silly mistakes.
Many students face the same problem of making small calculation errors, forgetting to keep track of positive and negative numbers, rounding errors, or any number of other small things that we all need to keep track of when taking a test. Most times these errors are even more frustrating because you understood the concept, you thought through the problem and planned your attack, and you felt confident that you were doing everything right.
This means you need to slow down. It isn't worth finishing a question 5 seconds faster if you miss half of the questions you rush through. If you find that you are making mistakes that you immediately see as mistakes when reviewing, that is a sign that you are rushing through questions and not giving yourself time to fully engage with the problem and your knowledge.
I make some very specific mistakes.
This is the ideal situation! If you can pinpoint specific skills or types of questions that cause you trouble, you can target them and improve quickly. The error log really shines when it comes to specific or patterned mistakes, because you will easily see if algebra or reading comprehension or some exact part of a test section is disproportionately represented on your log.
Remember, academic abilities might not immediately transfer to a given test. That is true even when those abilities are substantial, so don't think mistakes mean you don't know your stuff! Standardized tests represent an artificial environment of sorts, and they differ in important ways from the environments in which you normally perform your skills. Learn from your mistakes by recognizing what aspect of the test environment is causing you trouble (format, timing, knowledge, etc.) and tackle that head on. You should notice improvement, but it will take time, so make sure to be patient with yourself!