My second year of law school involved a number of thick statutory supplements. First semester, I marked the important stuff using Post-It flags, which which quickly bent, curled, and became useless. Second semester, I got smart and used Post-It Tabs.
They don’t bend, and because they’re a little sturdier, they make it faster to locate the stuff you need. I also use them to mark all the Bluebook rules that I know exist but whose details never quite stick in my brain.