Yes, interaction with someone is a must... (I say that without having benefited from anything but casual interaction w/ Japanese friends)... You need some sort of feedback about your pronunciation. I agree w/ Stuff because I suffered from the same thing, I went on a book buying/searching phase and didn't get as much studying done.
One thing I will suggest, is that if you do get some study material, try to get something that stresses use of Katakana/Hiragana with a gradual usage of Kanji... you can't avoid this as some programs (Pimsular) would like you to believe, and you need to get used to these things because things won't be written in roumaji...
I really like Japanese for Everyone, though I had to order cassettes from Japan, and they're still only cassettes, also, there is only one book, and no follow up, but I really do enjoy it's emersive technique. Some people will say Situational Functional Japanese, I'm not too ready to spend $75.00 per workbook plus the same for notes, 3 times over... I'd just go study in Japan by that point.
Good luck.