Good work SerpentPanda! Great to hear a 12-year old being so motivated to learn and willing to ask for and listen to advice from others.
Back to your question, I don't think you are quite ready for Genki 2 yet, and I would totally recommend you to get Genki 1. I started off with Genki 1 probably at a similar level you are now. I knew all the hiragana and katakana. I knew some basic grammar (learning from various websites on the web) and had a limited vocabulary. I also know Chinese, so I pretty much can recognize most of the kanji, but since you know about 100 kanji, that should cover most of what Genk 1 covers anyways.
I studied about 4-5 hours a day and it took me about 10 days to go thru Genki I. I breezed thru the first 3-4 chapters, but the exercise and the later chapters I found very useful. Although I knew some basic grammar already, the exercises really consolidated and reinforced what I learned. And I think at your stage, the most important thing is to build a solid foundation, and that's what Genki I will provide you if you follow the textbook and do all the exercises. I found that after Genki I, most of the common phrases, constructs and grammar became automatic that the studying afterwards became much easier. So even if Genki I might not last you long, you are probably better off in the long run if you know the Genki I stuff very well, than to stuggle thru Genki II and having a somewhat mediocre understanding of the material from Genki I and Genki II.
If you have the cash, I would recommend getting everything (Textbook, workbook, answer and student CD set). The first thing I'll skimp on is the CD, then the workbook. I think the answer is really useful because it makes sure I get the answer right, plus the answer book also has answer for Genki II, so you don't have to buy it again.
If you end up getting Genki, try doing all the exercises, even the ones you might find really easy at the beginning. Another thing I would recommend personally is to put setences you learn in Genki into an SRS (do a search on AJATT in the forum or google). I started using SRS half way thru Genki I, and I can personally attest that the combination of the two works really well in learning vocab, grammar and common sentence structure (I wouldn't recommend doing AJATT without any textbook though)
Hope this helps and good luck learning!
Last edited by zxcjason
on Wed 01.02.2008 6:36 am, edited 1 time in total.