"You don't know, what you don't know" was a life lesson I was too slow to learn.
Learning skills before we need them is one of the best ways we can stay safe and enjoy our bushwalking experainces. The following articles are good starting points to help you prepare for walking the Overland Track.
Supplement your reading with real life practice. Start with some short walks and build up over time. Do a few overnight walks before you set off on a week long walk. Learn from friends, test your gear and skills in wet and dry weather. Don't just plan to walk the one track, use this as an opportunity to discover great walks near where you live and enjoy walking in different places.
Information here also includes some more general bushwalking skills to help in get out and enjoy other walks before and after the Overland Track.