The best way to study for the SSAT/ISEE is to take a diagnostic test before you begin studying. Score the test so that your areas of apparent strength and weakness are clear. Then, go to work in your areas of weakness. If your area of weakness is word knowledge, study vocabulary religiously every day. There are a number of good books on vocabulary development which I use when I tutor SSAT/ISEE students. Analogy questions can be broken up into various types of analogies, and when the type of analogy is uncovered, it is much easier to make a match. It is important to practice, practice, practice, analogies. Reading comprehension is another important part of the test. Find the shortest paragraphs and answer those questions first. Always read the questions before beginning to read the paragraph. Most of the answers can be found in the paragraphs themselves, and eliminating answers that don't belong at all will give you a better chance on finding the correct answer. The essay portion is not scored, but a copy of it is sent to the schools where you applied. It is important to take a stand in your essay; choose one side or another. Have an introduction, at least two body paragraphs with a topic sentence, and specifics backing up each point, and a conclusion. It is helpful to work with a rough outline.
I'll blog about the math portion of the test on another day.