The most important thing for me was to grab some old JLPT4 tests. If you don't know the question types etc, you'll lose time (there were links in some older threads here).
Try to learn the words in context, that makes it easier to recognize what a sentences means. E.g. don't learn "migaku", learn "ha wo migaku" - that's what they will ask you.
Avoid romaji. Most of the test is in hiragana. You should not only be "able to read", you should be able to read it *quickly*. Also, pay some attention to katakana, the test will try to fool you with these.
For remembering the kanji I can only to suggest to use some "decomposition" method. That means, don't try to learn a kanji as whole, but split it in logical parts (e.g. like [suki] = "mother" + "child"). Maybe you can remember 100 kanji the "brute force" way, but later you'll forget them and confuse them with new ones. Beeing able to write them helps (try to follow the stroke order). Also, try to learn kanji "in context", use a word you can remember easily as "hook" (for instance, I used the word volcano [kazan] to remember the readings of fire and mountain).
Last hint: Browse this forum