I've spent the last 9 months since graduating working as an electrical engineer for a building services consultancy.
First thing you want to do is make a site wide single line diagram. This will have your main power distribution from the incoming power (HV/LV transformer, or utility feed in) to each switchboard (and how each switchboard feeds off another if cascaded that way).
Second, make a schedule of circuits in each distribution board including breaker ratings (ie 3ph 250A breaker, 1ph 63A etc).
Third, determine which loads/outlets are connected to each circuit.
You need to work logically from the top down, rather than starting at the outlets, otherwise it'll be a nightmare.
Hopefully the installer did at least some documentation. A list of circuits within the distribution panel door (sometimes in a plastic holder), labelling of circuit cables or outlets, has to be something otherwise it would have been hard to install in the first place!
Once you have a proper schematic of the layout, you can begin to do load logging and see what is drawing power and how much. Tripping sounds like an undersized breaker or incorrect trip settings.
It get's to be a lot more fun (and a bit of a nightmare) when you have to create proper 3D layouts in something like Revit