I'm at least moderately skilled in repairing them.   

Look into FHA 203(k) loans for repairs and down payment assistance programs in your area.

What leads to the highest repair cost? 

The real property investment can be repositioned if it proves disappointing in its original form; it can be refinanced or recapitalized if it has too much or too e pensive debt; inflation over time bales out many bad purchases, and finally the investors knowledge, experience and abilities can be leveraged to turn around a cash flow negative property.I’ll provide an exampleThree years ago we purchased a note from a bank secured by two auto repair facilities with a large amount of excess land.  

To stay secure, I’d recommend saving 3-6 months of mortgage payments, budgeting for repairs, and possibly investing in a home warranty.

The study could also identify the opportunity to capture additional benefits such as dispositions, and repair and maintenance expenditures.

Subtract more for AirBnB charges, local management, repairs, cleaning, etc and there is not a lot left to pay the mortgage. 

A few others have called out Hemlane, who appear also quite responsive here on BP and also offer a degree of repair/work order management baked right into their middle/upper tier offerings (versus having to bolt-on as with RentRedi + Latchel). 

Be conservative with your numbers – When using a cash-on-cash calculator, I recommend budgeting at least 10% for maintenance and repairs instead of 5%.

And that’s with zero vacancy, zero repairs, zero capex.