A friend who taught in Japan for 3 years sent me some advice on things to do...and not to do should I make to move to teach in Japan. I thought Id pass her advice your way, to see what you think, and if you'd add anything.
You mentioned reading. It really depends upon what you are doing with the information. Interested in Japan? Read. Gonna use it at work? Read (although you may never need such info teaching English). Wanna impress the locals (more to the point you wanna impress chicks) with your knowledge of Japan? Read. (Don't underestimate the power of impression with simple knowledge of Japan. I took a number of Japanese studies courses at uni and even the very simple stuff like significant dates in Japan's history, impresses the locals no end.) Have no interest in Japan, not gonna use the knowledge garnered in class, have a 12 inch dick? Then don't waste your time.
You mentioned something about running out of money in Australia at the bottom of your message. I have no idea where you were or what you were doing in Australia, but I can tell you this. Japan is much much much more expensive than Australia (salaries are also higher in Japan of course) so if you ran out of money in Oz, you should bring as much as you can to Japan because you are in greater danger of running out here. In other words, unless you are very careful with your money while you are not working here (while looking for a job and then waiting for your first pay check), it will be gone before you know it.
Further advice? If you are coming over for the purpose to save money, get a job with one of the big 4 and start looking for a new gig once you are settled. Ideally, you should try to get a day time gig, like 9 or 10am to 4 or 5pm, and then get a part time night gig. Usually the part time night gigs pay reasonably well. If you are lucky, you might be able to get one that pays really well. Or string some night jobs together, as the short time, like 2 or 3 hours a night, once or twice a week, often pay very well indeed. For about 18 months, I did exactly that. What I did was work during the day at one company, and then got a job at a juku (prep. school) teaching twice a week. I managed my schedule so that I could leave my day gig at 2:30pm (on the 2 days I worked at the juku) to arrive at my night gig in time to teach from 4pm to 9:30pm. My day job paid about 300,000 yen a month, and my part time job paid about 120,000 a month. That's not huge amounts of money but it left 3 nights a week and my weekends open for extra work. At one stage I worked a few hours on a Saturday but decided I couldn't be farked working weekends.
Once you get here and start working and making friends/connections, all these little jobs, and sometimes medium and big jobs, land at your feet. People leave, sometimes at short notice, which opens up positions. There is a lot of money still to be made in teaching English in Japan, but its a matter of motivation, hard work, managing your time/schedule efficiently, and a bit of luck. The only thing is that imho you can only do it for a few years as you get burnt out. Unfortunately teaching English is a lot harder than it looks or seems.
Come with an open mind and don't whine about things you are powerless to change. Whiny people (disproportionate amount of JETs by the way) are chumps, reviled by Japanese and foreigners alike. I doubt if many people intend to come over and act this way, but alot of people end up doing just that. You're gonna experience many differences in every facet of life here, and constantly pointing out how things are done better wherever you come from is just not cool.