Cap the tax deduction for rental properties at two & Only allow a tax deduction to people with a primary residence.
This will make sure there is still adequate rental properties available and not affect most mum and dad investors.
I have an idea for a range of light fittings for domestic and commercial use that have an internal Battery that is charged on off peak Power, and then runs in peak times on its own battery. Its not just cheaper. There's no blackouts!
Only allow gearing to a neutral amount i.e. Losses to match gains - that is neutral or positive gearing not negative eg if my rental income was $20000pa and my losses on this are $30000 then my allowable deduction is only a maximum amount of $20000