[BratGaki]

I have My japanese Coash too. It's pretty thourough. But don't use it alone. Buy lots of books, read Japanese learning/grammar sites, use your DS, download language software, get a dictionary, and use many sources to study. Some books cover what other's don't. It's never a waste to re-read lessons on grammar that you already know. Practice, repetition, and real-life usage are all important.