Valuing Property Features for ARV Comp Adjustments

[Justin Wolfe]

Newbie here. I'm in the process of looking for deals to do my first BRRRR. Right now the most difficult part is determining ARV of properties. In particular I am dumbfounded at conducting accurate adjustments on comps.

Amongst numerous Bigger Pockets sponsored books, I read J. Scott's guide on estimating ARV, but even this leaves me a bit lost. In particular he even admits that "(t)here are no hard-and-fast rules about how much various property features are worth -- this is going to be highly dependent on the level of house, the area, what is typical for local properties, etc."

Considering that estimating ARV of a potential deal is a crucial step to generating a positive cash flowing property that can be assessed for cash out re-financing at an appropriate price to re-coup 75%-80% or more of capital investment, this step above within ARV analysis is crucial to ensuring a good purchase.

With that being said, does anyone have any guidance, information, or advice as to how to determine the value of property features when pulling comps?  It seems that you will be standing confused like me on the outside looking in unless you actively work within a local market as an agent or contractor within a market.  

Any help would be appreciated.