The 1% rule is a flawed underwriting technique.

That isn’t “investing” or any “technique” it’s gambling.

When I first started years ago, I utilized owner finance and other techniques which most sellers would say no to if they didn’t meet me in person and see who they were working with.  

I learned almost all of my techniques for DD studying those memos.

Here's a https://www.irs.gov/businesses/cost-segregation-audit-technique-guide-chapter-4-principal-elements-of-a-quality-cost-segregation-study-and-report to the IRS website noting specific items that are included in the cost segregation study report.

Without these fundamentals there’s absolutely no way to utilize the various strategies and techniques being sold.

However, these are advanced techniques that are rarely as easy as they sound, and they all come with additional risks.

If the second property you are buying is not turnkey, will require some work, and there is a clear value/range of what you can bring the property to by adding value then you can refinance to pay back the majority if not all of your HELOC (used for downpayment or to buy the property completely).You'll need to know how to analyze an after repair value of the property to figure out if that technique can work or not.

The second Helmsley “negotiating” technique was not to negotiate.  

You can simply go to the Cost Seg Audit Technique Guide.You point to ATG?