The following is a list of recommended resources you can purchase.
You can theoretically use any notebook to study Japanese, but it is easier to use dotted notebooks like those produced by Campus.
Learn to write kana:
Write now! Write well! A Hiragana and Katakana Workbook (to write them in the correct shape)
Rokudo-Lines Method Workbook (to improve handwriting at the correct slant)
Studying the basics:
Basic Japanese (Practice Makes Perfect) (beginner students)
Japanese Tutor (advanced beginner to intermediate students)
Genki (2nd edition, they've only published volume 1 of the 3rd edition so far) (beginner students)
Minna no Nihongo (this is a package purchase, you can also buy them separately)
新にほんご500問 Book Series (practice questions, also available from jbox.com)
Studying kanji:
Kanji-kan Puzzle Book series
A Guide to Reading and Writing Japanese: A Comprehensive Guide to the Japanese Writing System
Practice reading in Japanese:
Let's Read Japanese series
Level 1 Volume 1 (advanced beginner, novice)
Level 2 Volume 1 (intermediate)
Level 2 Volume 2 (intermediate)
Level 3 Volume 1 (advanced low)
Short Stories in Japanese: New Penguin Parallel Text (Japanese Edition)
Japanese Stories for Language Learners: Bilingual Stories in Japanese and English (also available via Scribd)
Practice Japanese grammar:
Complete Japanese Grammar (Practice Makes Perfect) (intermediate students)
Japanese Tutor (advanced beginner to intermediate students)
Practice writing in Japanese: