This is probably the biggest mistake. Most students are afraid of "spoiling" the subject by looking ahead. But if you lack a basic understanding of how the concept you are learning today fits with the concept you will be learning tomorrow and next week and so on, you are hindering your ability to better learn the subject. Don't be afraid of spoilers when it comes to studying the law.
"Don't be afraid of spoilers when it comes to studying the law."
The fix: Start studying the subject by first getting an overview of the subject, or by reviewing a simple framework that outlines the general structure of the subject. Some professors' syllabi are detailed enough to do the trick, but you may find the need to consult a secondary source or study guide instead. Bar Secrets' PowerLaw gives you the basic framework in just about every subject tested in most law schools. You could start with that program (it's probably the most efficient and affordable option). Or you can spend more money for different materials, or spend the time and effort of assimiliating the law yourself. But whatever you choose, the goal is to get the 50,000-foot view of the subject before you start getting into the details. You will find you will learn the subject better, and memorize it quicker.