What I've done is use my PPoR and first four IPs all CC'd as security for a reasonably large LOC. I now keep all new properties stand-alone except for using the LOC for the 25% equity / buying costs required.

I find this a good compromise. I'm limited more by my debt servicing capacity rather than my equity, ie my PPoR and four IPs tend to provide all the equity I can use, so I don't need to cross collateralise any new properties.

The LOC can be divided into several sub-accounts which makes the accounting a lot simpler, but it's not essential. It is vital however,  to keep any private sub-account well separated from the investment sub-accounts. 
 
It's probably a good idea to keep any share investments separate from property in a big LOC as I've recently come to realise. I just shifted all my shares into my super fund (because I'm now at the age when I can draw a TTR pension) but in doing so, all that portion of my big LOC that was used to purchase shares is now effectively private debt. I can't pay that part out separately; I must apportion any principal repayments between the investment and private parts. The only way to kill my private debt now is to pay out the entire balance of my LOC.

Just one other point on Steve's portfolio. If you listen to his disc at the back of his book, he'll tell you he didn't have more than about 80 properties at any one time. He's done a fair bit of selling as well as buying.

This is all I've been able to find so far Gibbo:

The first-home buyers scheme will be time limited. All contracts entered into by June 30 next year will be eligible for the new assistance.
It implies that any new contracts started as of now will be eligible, but it may be a bit rough for anybody who signed one yesterday.

It depends on the percentage. 72 is more appropriate when the percentage is around 8%
Here's a table:
%    "Rule Of" Number
2            70.01
4            70.69
6             71.37
7             71.71
8             72.05
9             72.39
10           72.73
12           73.40

Here's the maths if anyone is interested:

   intRate = [int rate]/100
   [years to double] = log(2)/log(1+intRate)
   [72 rule] = [years to double]*[int rate]

S/C

ErikH, I'm extremely skeptical of any study that shows property increasing that much over such an extended period. I've seen other studies that show about 5-6% over the last 100 years for Australian property.
Let's look at the maths: 10.4% over 120 years is a factor of 143314.06. Can anyone tell what inflation has averaged over the last 120 years? I've had a bit of trouble finding a decent reference.
Assuming it was 5% gives a factor of 348.91which means a house now is 410 times more expensive than it was 120 years ago if the 10.4% growth is correct.
Even assuming inflation averaged 8% gives a factor of 10252.99 which means that a house is now 14 times more expensive. It just doesn't make sense that property can outstrip inflation by more than a percent or so over the very long term.

It seems Dixon haven't changed their spots for decades. Just thought I'd mention a Dixon home that was being built in our suburb back in 1986. The owners were so incensed with Dixon's slow progress that they erected a sign near their fence that read something along the lines: CLAYTONS HOME. Dixon were supposed to finish our house months ago; they are full of promises, but that's not all they are full of. etc etc. 
   Dixon builders pulled the sign down, but the owners called the police, who forced the builders to put it back up again. Strangely, the home seemed to be finished fairly rapidly after that.
  We've called that home the Claytons home ever since.

PS if any of you young'uns are curious about the origin of the term Claytons:
http://en.wikipedia.org/wiki/Claytons is an interesting read.

That's ok Alex, but remember you can only rent it out for six years with PPoR status, provided you don't have another ppor. You only have to live in for about 1 month to show ppor status. The six months is for the FHBG. You only have to live in it for another month in six years time to reset your ppor status. There's nothing wrong with the sharing concept. That's what I'm trying to get my kids to do. It's ok while they're single, but it's no fun when you're newly married and trying to put up with boarders. (that's what I did for six weeks and it s'd big time!)

Alex, you can claim the FHBG, but it would be best to do all that through your solicitor to make sure it's all done properly. You can also rent out your PPoR while you are living in it, and still keep your CGT free status for six years. It may be better to start living there by yourself for a month to establish it's credentials as your PPoR, but after that you have six years. All you have to do after that period is kick your boarders out for another month, and it resets again. I used to think the six year rule was only for when you were overseas etc, but I'm told by my accountant that you can still live in it and claim that rule. (You can't have any other property as your PPoR at the same time of course).
 If for example you get two boarders sharing with you, then you can also claim two thirds of the rates and interest as a deduction. You'll have to declare their rent as income of course, but it's probably much in your favour, as it will be net negative in the current climate. You can probably claim proportionate depreciation as well.