A lot of this depends on where you feel your weak points are, what style of learning you like, and exactly what your level is; I'd suggest checking on Amazon/elsewhere to see if they have pictures of the contents and how things are laid out.
Personally, I like the どんな時どう使う books. I have どんな時どう使う 日本語表現文型500, it's pretty much all in Japanese, has plenty of examples and test questions, and covers grammar points that appear in 1級・2級 JLPT.
e.g. the first section covers:
2級:について、に関して・に関する、に対して・に対する、にこたえて・にこたえる、をめぐって・をめぐる、向けに・向けの・向けだ
1級: にかかわる
There is a lower level book as well. I like the tests because they focus a lot on when you use one pattern rather than another. There is a lot of furigana (I suppose because this is aimed at someone who has passed 3級 and is moving on to the upper levels, but probably only knows JLPT 3級 kanji).
I also like Naoko Chino's books, particularly "How to Tell the Difference between Japanese Particles"; and Kakuko Shoji's books like "Japanese Core Words and Phrases: Things You Can't Find in a Dictionary" and "Basic Connections: Making Your Japanese Flow".
I'd also suggest, if you can, starting to read as soon as possible. This is the best thing for vocabulary. Material on a subject you already know pretty well in English is a good idea - if you knit, look up Japanese knitting blogs, if you go mountain climbing, see if there's a Japanese mountain climber's forum or something.
人気ブログランキングとブログ検索 - にほんブログ村 is a good way of finding Japanese blogs by topic.
If you have a lot of trouble with the grammar then you might have to come back to this later, but if you can find something where you understand most of the grammar used even if you have to look up words, then that's ideal.