- Checked my country's JET timeline on the Japanese Embassy website. Applying for JET is a long, and sometimes complicated process - the more you know about dates and necessities, the easier it will be.
- Found out more from people who have done or are currently on JET. You can do this online, or by talking to people you might know over there. There are heaps of websites, blogs, youtube videos, and if you don't know anyone personally, you can ask around and you might find a friend of a friend who has JET experience. This information is invaluable in giving you a realistic idea of the JET programme, although always remember, "every situation is different"!
- Attended JET information sessions. These are often held both at local universities and Japanese embassies. They also give great information from previous JETs, and you can hang around and ask questions afterwards.
- Got a previous year's application to look over. I went my local embassy to ask if the applications were out yet, and they told me they weren't, but that I could take a previous year's application to look over. This really was useful, just to familiarise myself with the form and the things I would need to fill it out (ie. a police check).
- Sorted out my references. I heard some people say that your references should specifically mention the JET Programme; for the record, mine didn't. I had one reference from my assistant teacher on one of my primary teaching practicums, in which my referree reccomended me for any teaching job. My second reference was from a language teaching lecturer from the diploma I did, in which he cited my exam score, my part in desgining a teaching tool, and my understanding of Intercultural Communicative Language Teaching, and reccomended me for any language teaching job. In hindsight, I wish I had gotten more than one original signed and letterheaded copy of each of these references for the future, as you have to hand in the originals with your application (they will not be returned).
- Wrote my application essay. You can see a draft version here: http://lovefromnippon.blogspot.co.nz/2013/02/my-jet-statement-of-purpose-essay.html
After I was given notification of my interview, I did a few more things to prepare. Mainly, I studied up on the types of questions they might ask, and brainstormed some answers as well as a list of my best attributes. You can get an idea of the questions I was asked here: http://lovefromnippon.blogspot.co.nz/2013/02/jet-interview.html
I also decided on an outfit and studied up on some basic knowledge of Japanese current affairs, language, and culture.
Hopefully this information can help you prepare for applying! If you have any further questions, just ask in the comments :)