It can be very difficult to make a living with all the associated costs to acquire and sell property (agency fees, legal costs etc) and if the market suddenly goes soft you can be in serious trouble if you can't sell the property for a profit.
This is especially true if you use another property as collateral for the loan.
That being said if you're confident in you abilities then go for it.
Personally I recommend property investors to take a land banking approach and and focus of cheap cosmetic renovations which offer a good return on investment. It's not as exciting as renovating and flipping property but it's a solid strategy.
If you decide to buy in Sydney's East get in touch
. Cheers