tips for underwriting rental properties

[Tatum Briggs Mead]

any tips for learning how underwrite properties? david has said to analyze one property a day but then I also heard him say that analyzing properties off the mls without actually meeting the contractors, calling for the cost of the utilities etc is basically just fake learning how to underwrite. I understand what goes into it and how it all works but am confused how to practice on houses when I do not know information like ARV and wont be able to learn that until I really start investing.

Any suggestions or tips to get better at the underwriting processes while I am working to save for my first investment would be greatly appreciated, thank you!