Today is very different as it is all about the management (and not appreciation) compared to past where management could suck but you still had superior apprecation.This will not crash housing of course but all those "creative" deals where people are paying more than market value are going to realize they have no exit. 

Still use paper method for mileage logs.Tried QuickBooks several years ago but it was more complicated and I did not need the bells and whistles.

These methods include: Detailed Engineering Cost ApproachDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling ApproachExperience or “Rule of Thumb” ApproachIt’s important to understand the differences between the approaches including which one best fits your property and the reliability of each approach.DETAILED ENGINEERING COST APPROACHThis approach compiles the costs from construction and accounting reports to build a report.

Quote from @Stuart Udis: ....But I set the goal of acquiring 50 doors in the next 3 years using the BRRRR method and will then be financially free...isn't that a scalable business :)We see the above type comments from not so experienced investors or business owners all the time being posted on BP.  

As Jay and I have warned, WAY too many of the people grasping to this SubTo method SHOULDN'T do it.

Not the most scalable method, but I like the benefits it affords me while I am still a smaller operation.Completing 500 builds in just over 10 years is impressive for someone who just sorta fell into it.

Any recommendation for the first steps I should take if I want to purchase my first rental property using the BRRRR method (or flipping).

You can definitely spread your cash out pretty far here using this method and scale pretty quickly with the right boots on the ground team!

Was looking to save where possible in this market but the method I proposed is not worth the consequences. looks like 20% down it is!

I would encourage you to learn the market you plan to invest in now and to continue to learn about the different methods of investing.