1) PERSEVERE! - Find something to keep you motivated, I am aiming to be able to watch anime raw, be able to make normal conversations, hopefully native-level eventually, with native speaks if I can ever visit Japan. Also try to do different things that immerse you in the language, such as listening to Japanese music (Asian Kung-Fu Generation), trying some raw anime (which you can do here on Crunchy) or manga once in awhile, and so on. You could also, when you feel comfortable enough, try setting your electronics to Japanese, such as your iPod or Laptop (Apple devices are much more non-english friendly, especially the typography)

2) Start with inexpensive software/texts, and work your way up to more expensive stuff if you need it. Not going to diss Rosetta Stone, but I've never used it don't plan on doing so anytime soon.

3) Practice reading and writing kanji (and kana)- there are many different things to cover with kanji: Stroke order, direction (both are almost natural after practicing various different kanji for awhile), on and kun readings, kanji with made up readings (>_>), and names. Some kanji have more than 20 different readings, by themselves, for names.

4) Don't use romaji - unless your learning kana - simply put, this is the biggest hinderance you could have in learning Japanese. Once you learn the kana (hiragana and katakana) don't touch romaji at all unless you've forgotten the readings of a certain kana or such.

5) Don't be scared of all the rules and such - Japanese might seem extremely different from English (it is), but don't let it discourage you. Just picture yourself as Natsu (from Fairy Tail) and Japanese as something that's utterly impossible (take it as a challenge); but it isn't Spanish or French, it's an oriental language, so it's going to be more difficult.

6) Try to work your way into native level texts - working with "Japanese 101" books in english is totally fine for the first while, but try to work your way to books that are written in Japanese. One I'd recommend for somebody on a level of moderate understanding of the language (I have no idea how to compare comprehension or ability) is the すぐに使える実践日本語シリーズ (Immediately useful - practical Japanese workbooks series), specifically the ninth volume, as it deals with beginner and intermediate uses of particles, which are extremely vital and also some very big obstacles (such as the difference between は and が).