The best way to learn is to set a consistent schedule, which includes both immersion practice and some form of flash card practice. There are many fantastic guides out there, but they all boil down to these basic points.
1) Learn Hiragana and Katakana. It doesn't really matter how, but this is always the first step.
2) Begin learning basic vocabulary and kanji with the assistance of a flashcard system like Renshuu. Using a deck like N5 or Genki is a good start but there are many beginner decks.
3) Spend time immersing in the language. Reading, listening, both will help you see the language being used and will help you to understand the language as it was meant to be used.
4) Use a grammar guide. There are many, and Renshuu has a nice one built into it.
I'd recommend you do 5-20 new cards a day (5 being slow, 10 being average, 20 being intense). Give it a few years and you'll be fluent! The more you immerse, the less time it will take, but remember the key is consistency NOT cramming in a day and then doing nothing.
