Brainstorm about the "Erie Doctrine" so that you can spot the Erie question on exams. The Erie question will come up only when parties are in Federal court based on diversity jurisdiction (if you're not sure why, take a minute and think about it). Your fact pattern will need to contain some kind of state statute. Often, there will be a federal statute that potentially conflicts with the given state statute but sneaky law professors don't tell you about the federal statute. Instead, they give you a state statute that is very similar to a FRCP and its up to you to realize that the FRCP is the Federal rule that is used in the Hanna analysis.