I've been studying off and on (mostly off) for the past... nine years or so.
The hardest part of Japanese is learning the kanji, then the kana, and then everything else is fairly simple as the grammatical structure is pretty straightforward, and the number of irregular verbs in Japanese can be counted on one hand.
As far as memorizing kana goes, just writing them over and over and quizzing on flashcards worked well for me.
I'm still working on kanji, so I don't have any tricks for that.
As far as learning the words and the grammar, I took a couple classes, own a couple books, and I watch/listen to a lot of programming and music in the language so I can hear it being used.
I'm saving up to invest in Rosetta Stone, because I hear it's a great way to learn.
I haven't practiced Japanese much after taking AP Japanese, ahahaha. What I find best is putting yourself in a situation in which you really need to use the language. For example, attempting to hold a conversation with someone fluent in Japanese or reading a Japanese book. (or, in my case, manga lol)
I learnt the wrong way, through watching too much anime. I consolodated that knowledge by reading a book on 'learning Japanese for dummies' and listening to Japanese TV/Radio: always the best way to learn languages in my opinion, there's nothing better than hearing people who have the language as their mother tongue speaking it.
I am. My advice would be to start with CORRECT pronunciation from the very beginning and focus on learning all the kana along with it. Those beginning steps will help immensely. At least it did for me. Japanese for Busy People Kana Version is great for beginners as it forces you to read all in Japanese and it's basic enough to start off with.
I started an introductory course about about a year ago and lost interest. Unfortunately its nothing similar to any european language in terms of its structure, so it'll be completely foreign to you when beginning. Also keep in mind the written language is also completely backwards from what you're used to in english, so you have to have a real interest in learning the language before taking it up.
These are all great tips, but I meant more in the direction of advancing in the language than just beginning. I've been slowly learning since about 7th grade (roughly 5 ish years.) I think my level is sorta above elementary, but still pretty below intermediate.
I'm learning Japanese .
What I'm trying to do this summer is learning the kanji on this page: Category:Grade 1 kanji - Wiktionary
Once I've mastered these I'll go on with Grade 2, etc etc.
What I find very, very helpful is reading the etymology (first paragraph of most pages) of the characters, so that's the origin of the characters.