Here's my own recommendation:
First, take a few days/weeks to learn hiragana and katakana, just by writing them out until you can remember what they look like and what they sound like (you can find the stroke order in a lot of textbooks, or online).
Next, buy volume 1 of Minna no Nihongo (volume 1 consists of two books).
Then go through each chapter; for each chapter, learn the vocabulary off by heart, learn the conversation off by heart, read the grammar points and sample sentences, and go through the exercises. It will go in. But you have to be methodical, and you have to learn stuff off by heart, and you have to try to do it regularly, and if you listen to the japanesepod podcasts at the same time it will only help.
If that sounds too boring, you could always try this
guy's technique, which is to learn lots of Japanese sentences using spaced repetition software.