practice, pratice, practice. write, write, write. the more you write in japanese the more you remember.

The best way to learn Japanese writing is to master "Jōyō kanji" (essential Chinese characters) as much as possible, & both Hiragana and Katakana, which all derived from different Chinese fonts, are also the necessary parts. Note: Jōyō kanji = 常用漢字 (じょうようかんじ). Perhaps it wouldn't be an effective method to learn Japanese only with Latin alphabet.