There are some basic principles for people who are trying to prep on their own. Crafting studying technique is something more tactical, and personal, that you'll have to do on your own, based on what you know about how you best learn. Most of these, apart from distinctions as noted, apply to standardized tests in general:
- Start by creating a realistic schedule of daily work. Because the daily part is important, realistic probably translates to 15-20 minutes a day. "I'm going to spend two hours a night" is well-intentioned, but unlikely to happen.
- Use only the official materials. There is only 1 published book for the GRE.
- Materials include practice problems and practice tests. Do the practice problems first, then do regular practice testing as the actual test date approaches. There are two official GRE practice tests that are free to download. Because the tests are adaptive, they can be taken multiple times. You can get away with around three sittings per test without significant overlap, so that allows you six practice tests. These should be taken once a week for the six weeks leading up to the test, in an environment that simulates the actual testing environment as closely as possible (e.g., wake up and start the test at the times you would need to, isolate yourself in a distraction-free room, don't let yourself listen to music, put your phone somewhere else).
- Find someone with whom you can review the questions you get wrong. This doesn't have to be a professional if that's not feasible for you, but it should be someone who's good at the relevant content, or has scored well on the test before, or both.
- Do more practice problems for the content areas that seem to be surfacing the highest frequency of incorrect answers on your practice tests.
- Though there is no official vocabulary list, GRE prep requires studying vocabulary. Antonyms and analogies (and, to a lesser extent, sentence completions) lean much more heavily on sheer vocabulary than the passage or vocabulary in context questions that have largely replaced them on tests like the SAT for precisely that reason
Finally, just to underscore -- consistent, well-planned preparation is key. On tests like the GRE and the GMAT, cramming is basically a giant crap shoot.