Depends who was doing the invading, if it was the US Army I'd likely stick around and just chill, I might not like it, but at least they worry about the press jumping their shit and wont start shooting us out of hand.
If it was China or a nation that thinks "human rights" is something sci-fi authors made up, my family and I would be out in the bush so fast you're head would spin. We've got a store of fire arms (all legal), ammo, and actual tough non-trendy camping equipment, plus we all grew up in rural areas and know the bush like the back of our hand.
I personally could survive off the land for years with no trouble, and so could they. I don't give a shit how good the invaders are, they aren't going to find anyone who doesn't want to be found in the Australian bush.
I doubt I'd do more then ambush the occasional patrol for supplies, don't want to draw attention to us, I'd be more concerned with keeping my family safe... at least until tech withdrawal started to set in and then the bastards would be in for a world of cranky angry nerd that has actual survival skills, marksmanship awards, and a shaky sense of reality and morals.
