How to "practice" an analysis

[Abbott Mary]

I'm rereading Frank Gallinellis' book on cash flow and 36 other financial measures, and I find myself wanting to practice his analysis principles with real life properties (so much so that I've taken a break form reading it to post this), however I'm not sure if what I typically end up doing can be really called analysis.... as it usually ends up resembling just a very structured form of guessing. I will begin an analysis, and going down the annual property operating data sheet I probably won't make it a third of the way down before I get to some information that I would at the very least need to have the property under contract to truly verify (obtaining leases, operating expenses, tax return from seller etc...). In addition, the typical expenses that would require a thorough walkthrough/inspection of the property to truly determine (updates, maintenance, Capex). When I work my way down the list, It seems that I end up with a very shaky list of estimates that are almost entirely the sellers data and none of my own. So my question is this, when practicing analysis are you just simply practicing the input of seller data into your particular analysis tool and not actually verifying the information?

Sorry for the long winded question. I'm just very excited about multi-family investing, and I'm looking to get as much practice in as possible before I'm ready to purchase my next property.