No point getting a twin endo before heading out into charter as the training school twins are rarely the same as you will see in charter. Unless of course you actively seek a school with a islander or baron, AC50, chieftain etc to do your initial twin endo in...
Having your initial IFR before heading up North could save your bacon and give you that little edge over your competitor when applying for jobs!
What ever you do, don't waste you money on a single engine IFR or doing your rating in some fancy glass cockpit...
Can highly recommend Bob Harris in Innisfail or John Chew (somewhere between Darwin, Cairns and Melbourne)
Best of luck