I finally start seriously studying for the written. Hours of reading regulation after regulation from the FARs and page after page from the AIM. It's mostly in-one-ear-and-out-the-other, but some of it sticks. As for most people I know who've done this, the regulations are the hardest part: it's one thing to have to nut out an answer to do with (say) VOR navigation or weather trends from first principles and a smidgeon of logical thought; it's quite another to have to answer questions about regulations that don't seem to be based on anything physical or logical. It becomes a process of trying to memorise a large set of arbitrary facts -- like the maximum airspeeds in holding patterns -- that can't be derived from first principles (or much else, for that matter).
The "written" test is actually a computerised multiple-choice test administered by the FAA, and it's a weird collection of fairly straightforward questions and deliberately (and annoyingly) tricky questions designed to catch you out in ways that just don't reflect real-world problems. So preparing for the test is mostly just divining what the FAA thinks is the correct answer (they don't publish the correct answers anywhere, let alone any sort of explanation or the thinking behind them), and learning these by rote.
I use the Dauntless Software test prep program on my laptop for this. It's very effective at identifying holes on my written test knowledge and getting the "correct" (FAA-approved) answers burned into my poor little brain (I used an earlier version for my PP-ASEL test prep). So I sit there in front of the laptop, a rat pushing levers.