Law School
What exactly is the deal with outlines? Do you buy them? Make them? Get them from other students? I've heard them mentioned several times, but don't know what the hell anyone is talking about.
It's basically an outline of the course notes, distilled down to the core concepts, (very) brief notes on landmark cases, and the rules/exceptions that you've picked up from the course. I tried to keep mine down around 15-30 pages (in outline form, so it's not really that long). Sometimes you'll hear people bragging about their 100 page outline...that really defeats the purpose.
Like Taz said, most people do all three. During your 1L year, you'd definitely be doing yourself a huge favor by making and revising (and revising...) your own. Keep it fairly skeletal your first few weeks and try to flesh it out a bit once you've got your bearings (All 1Ls waste a lot of effort during the first few weeks of school, it's just the natural way of things; I think that trying to keep a fully-formed outline for, say, the first 4 weeks of 1L year is one of those exercises in futility).
Find out if you're allowed to bring outlines into your exam and tailor it accordingly.
Outlines from past students are very helpful for studying and seeing the forest for the trees (to that end: the earlier you can get one the better), but if you rely solely on them, you won't force yourself to piece together the information you've been given and see how it fits into the course. Making your own outline is the best way to learn the core material and to begin filtering the less important information (which comprised about 95% of my first semester notes).
Commercial outlines help you track down any important details you might've missed. These become much more useful by 2L year when most people abandon outline-writing or at least trim them significantly unless the exam is closed-book, open-outline. By 3L year, you abandon reading, note-taking, going to class, studying; commercial outlines
are the course. It's a hard life.