So far, only two things I feel safe in saying I would do again:
1) Study for your last exam first.
Three days between exams seems like a lot when you're looking at it from a month away. It's not. I don't know yet whether anything I did will yield where it counts (in grades). But I do know that if I hadn't spent a week doing focused exam prep on Ks before classes ended, then I would have gone into the exam with no more than about 12 hours of concentrated review. Also, the further you get into those last couple of ugly weeks, the more people will shut down, so that last exam may be your best chance to climb the curve a little. Once classes end, things just come unhinged, and you will be sucked into spending all your time on whatever horror is next at hand. You will also be be wrecked for 12-18 hours after each exam (at least I was), so you have precious little time to do anything that is left undone for the second and third in line.
2) Put as much time as you can stand into your legal writing assignments.
Lots of people will say it's stupid to do any more than you can possibly get away with for a P/F class. But this class -- and nowhere else in 1L -- is where you are really going to learn to "think like a lawyer." Doctrinal classes are going to bury you in cases (100 in three months on my Ks syllabus), and by the time you even get half a sense what one of them means, you're on to the next one. In legal writing you have the chance to learn how to read a line of a half-dozen or so related cases in depth, all from the same jurisdiction and on the same point of law. And you will learn how to form that flock of scattered, half-baked, rambling, contradictory "holdings" into a solid, working legal argument. It is damn hard learning the difference between stating a point and arguing a point, and here is where you have the chance to spend enough time on one point to learn that.
The one problem with this is that there are good legal writing instructors and there are awful ones. I learned more in legal writing than in any other class, including in areas that are crucial to being able to study productively for and function coherently on final exams. That was entirely due to having an outstanding legal writing instructor who was a practicing litigator for years, and who gave endless amounts of solid, direct, useful advice -- no silly games or tedious, self-indulgent academic diatribes. One of our other sections had an instructor who went out of their way to make the class a hateful, pointless chore. In that spot, I probably would have gone the route of doing the least I could to get by.
3) Commit two or three hours a week, every week, to a substantial pro-bono or service activity.
If you can get into clinics as a 1L, then that's a great start. Like legal writing, this will teach you more about the law in two hours a week than you will learn from all the rest of the silly crap you do in the first year combined. If you don't have access to clinics, then sign up with some organization like Street Law or just volunteer with a student group or a local agency that does real legal work. Do some research and writing, client intakes, basic pleadings, outreach and education -- whatever. Lets face it, if you don't do this, then you're just going to piss away most of those couple of hours playing Wii, getting blitzed, or just plain procrastinating anyway, because nobody ever studies as much as they should (or at least as much as they think they should). When you find yourself solidly in the middle of that 90% who don't wind up in the top 10%, you better have something to show what you did with all that time that you obviously did not spend rocking the curve.
Don't get me wrong -- grades come first, because this is after all law school. But remember that there is such a thing as diminishing returns to spending all of your time studying. After a certain point, the people doing unreal amounts of work keep going just because they have no idea what they should be doing, but they think that more work can never hurt, no matter how senseless it is. A lot of 1Ls will do almost no productive community or volunteer service their first semester, because they're afraid to "overcommit." But you will find endless ways to "commit" to avoiding all of the work that you know you should be doing at every turn. And there will always be more that you could do, no matter how much you get done. Make sure at least some of those hours that you spend avoiding law school will leave you with something more interesting than "J.D. Candidate, May 2011," to fill out that shiny new section of your resume.
Ok, so that's three things. I'm saving anything else until grades come back.