Practice reading small, informational excerpts of texts quickly. The SAT doesn't look for the most entertaining samples for their tests. After reading, see if you can explain what the piece is about and any complex vocabulary used in it. Vocabulary books are helpful, browsing any local bookstore will show you numerous versions, but you must be willing to go beyond just drill and kill. Practice the words; use them with your friends or at the dinner table with your family. How did you learn to talk? Flashcards or by using words (even if you used them incorrectly? Someone corrected you and you learned. Beware that words have multiple meanings. Standardized tests love to use different nuances of a word to make sure you really know how to use .
The biggest one is to try and do anything you can to increase your vocabulary. This is just SO key to get a good mark in your SAT. When I have tutored SAT students, I have downloaded lists of more challenging vocabulary from the internet and gone through them doing various activities to help learners learn them, from getting them to use them in their work to playing games with them. Vocabulary is key.
As mentioned, these are all fine suggestions. (Practice exams and info. available today online are great suggestions.)
Reading is so very important, but not just the reading—the recognition of words strung together—but a clear understanding of what is being read. It might be valuable to read poetry as well as fiction and non-fiction. Practicing to understand what is meant in the reading is important. This might be accomplished by reading a poem and then checking (on eNotes!?) what other people believe the poem means. Literature of any kind certainly carries the freedom of personal interpretation. However, knowing what a piece says before interpretation is a pre-requisite for the latter.
Writing is important. Too many young people believe (as has been my experience in the classroom) that writing is not important. (This is a common belief with regard to reading as well.) Somehow young people think that if they are not going to be English teachers, that reading and writing are no big deal. Well, they are. Students need to realize this as early as possible.
Increasing vocabulary is important, too. However, if a student reads at their age leve or higher, this will help to improve vocabulary. It would be helpful, too, for students to try to find the meaning of a word through context clues. This is easy enough to do if one reads, makes note of an unfamiliar word, and jots down what the word seems to mean, to check with a dictionary later. Students don't have to read the dictionary to improve their vocabulary.
Finally, restful sleep the night before the test, a good breakfast, and water and a pack of gum (if allowed) during the test will not only prepare the mind and body, but water and gum provides additional stimulation when the length of the test begins to wear.
All the earlier answers are great. When I was studying for my graduate school exams, I used a method known in the Renaissance as "the house of memory." The idea is that you link key ideas that you want to remember with objects in rooms of your house -- rooms with which you are very familiar. In your mind, you associate ideas with specific objects and then, when you need to think of the idea, you "move around the room" mentally, in an orderly fashion, and you can think of ideas that you would not remember this well if they were not organized in this way.
The method is mentioned briefly near the end of this article: http://en.wikipedia.org/wiki/Art_of_memory
It actually did help me.
There a lot of good study-guide books available in book stores, but I would specifically recommend looking for one that breaks down the skills into specific "lessons" at the beginning of the book and then has small practice exercises to "practice test" those specific skills. This would be especially useful in the English section where there are punctuation rules, verb rules, pronoun rules, etc. that when studied together can be overwhelming, but taken in small bites can be more thoughtfully studied and practiced.
Read, review, read, practice, read, prepare, read,... Using practice exams to identify the areas in which your current knowledge base is weakest will allow you to spend extra effort brushing up in those areas.
And, don't forget some of the last-minute obvious preparations. Get a good night's sleep and get up in time to have a leisurely and healthy breakfast. Arrive at the exam location early enough so you have time to settle in and calm yourself before instructions are given and materials distributed.
Practice exams with diagnostics that isolate the areas you need to study for the most are the way to go. The SAT assesses a pretty broad range of skills/knowledge, and effective studying is focused studying. The College Board releases practice tests, and there are many available on the market of varying quality. Many high schools offer SAT prep courses, I'd highly suggest enrolling in one if possible.
I would suggest reading as well. Given that the SAT focuses upon vocabulary, you need to check out the most used words on the SAT (you can Google it). I would also suggest taking practice exams. You can find those on-line as well.
The earlier a person starts, the better a person will do. I would suggest the following. First, a person should get into a habit of reading. The more a person reads, the better a person will do generally speaking. Reading develops a person mind in many important ways. Second, a person should also systematically memorize typical SAT words. Finally, I would suggest that a person take practice exams. This last suggestions is the most helpful.
For the SAT, take as many practice tests whenever you can. If you don't have enough time for a section or a entire test, go on collegeboard and do the SAT question of the day (linked below; there's also an app for it on smart phones). Another thing you should know about the SATs is that they will always have the same types of questions & format unless stated otherwise. Review and follow up on them before the test. In addition, be familiar with the directions of the SAT before the test so you don't have to waste time reading them during the test.
The earlier you start the easier it will be. Take as many practice tests as you can this will greatly help you. Take SAT practice books and set time aside to just work on it. Also review SAT Vocab.
Depending on your level in math, take the SAT as early as possible. For most of my peers, this meant the end of sophomore year (we took pre-calc in freshman year). Prepare all 10th grade long for maybe 3 to 5 hours a week. Up the number of hours as test day approaches but don't do any prep the night before.
Take all the practice tests you can.