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.