Nothing is fool proof, but simply owning low cost rentals where you can afford to drop the rent and undercut most of the competition seems prudent.

Not foolproof, but works most of the time.

Personally, I'm one of the laziest people around, I hate hard work, and I would pay a king's ransom for a foolproof system!

This is not foolproof as a lot of areas where everyone has dogs tend to have gates because dogs can tear through a screen door (when left open).

That is not to say it is foolproof or that there is any guarantee the bank would not call the loan. 

It has a tutorial that walks you through exactly how to use it, which is foolproof.

This is not the first time I've listened to a guy named "Ari" tell me he could sell me a foolproof system for making me money, and every other time in that far-off land where "Ari" is a very common name it was not 2 Legit 2 Quit, no, no, no, filoi kai aderfia, not by a long shot.In any case, the biggest problem, the bottleneck that keeps us from scaling up our ghetto BRRRRing quickly, isn't the cost of borrowed money to keep up with deal flow, it's the lack of affordable competent renovation tradesmen to plan, manage, and carry out the renovating.

One of the little tricks I tell people to use, though it isn't fool-proof, is to use Google Earth to take a virtual walk around the property's neighborhood.

I am not fool proof and have/do go over budget.

Buying income property for cash-flow and using depreciation to offset rental income and tenants to pay off your mortgage is pretty fool-proof.