I agree with sacred. Learn how to speak it first, then once you get it down start writing the alphabet. Act like your a kid in kindergarden and have to learn everything over, now give yourself assignments dealing with writing japanese.
Also, if you want to learn cheaply, I suggest buying a japanese to english dictionary or better, a trabel book that teaches japanese for the traveler heading to Japan. Thats what I currently have and so far I have learned more than I ever did using free sites.
Or you can take the approach of asking a japanese speaker on this forum to tutor you. Once a week is enough, and when you arent being tutored you study from books, sites, etc.
Secondly, I highly suggest you learn particles, sentence structures etc. I started learning words and sentences and sure, they help but when you can form your own sentences then you are mastering the japanese language.
Japanese-Online.com
Google
And remember, when in Japan, anyone who pisses you off seriously, call em' a baka, big insult to the japanese and perfect insult for those who just cant stop bothering you because you are american. Though I doubt anyone will hassle you since the japanese are always on the go and ignore most people
~Arigato, Ja Matta~