If you're at all serious, I would absolutely not recommend self-study as a beginner. You need to get into a classroom where you're being taught by native speakers. As far as a textbook, find out which textbook your college or university uses. When you move into the 'intermediate' level, self-study becomes more practical because you'll have the resources and knowledge to begin answering your own questions.
I agree with skrhgh3b's suggestion, since i followed that path. It's damn hard to start from scratch, let alone deciding which is the 'correct' path. With a teacher, they can guide you for the beginning of the journey. Once you get a kick start, you can then do self study.
In my case, I had a teacher for 6 months and the rest was self study. I must admitt, i did learn more without a teacher but she did guide me and gave me the perfect kick off to japanese learning.
In your case, fliprenegade, you have no time for actual classes. So, good luck with your self studies.