I know it can be a little frustrating Jim but its also a little hard to put on to paper.
Think of it this way - Anywhere mainly in the lower sections of the body may be rusted ,Bogged over ,Braised in repairs - which reacts and causes rust, or just bodgy replacement panels.
As looking for most of this is common sense it would work out to be an essay to write what to look for.
My advice is to know what rust looks like -Know what bog looks and sounds like, and dont be overwhelmed by the cool car you could buy, There will be more available and your patience is invaluable.
If you see rust (Use a torch to see under the car, A magnet to find thick bog which isnt always rust underneath anyways) Use your common sense and imagine how difficult, Structural, Or large the area will be to repair also taking into account rust grows and you will almost always cut out a very large area around visible rust to have good metal to weld too (rusty metal is thin and impure and will melt when hit with a welder.
Main points on FE/FC = Floor pans caused by leaks from bad seals mainly.
Lower area behind front guard - Build up of dirt spatter off front wheel, Does affect headlight peaks .
Sills = years of built up dirt carried in through small areas towards the front via vibration wind water etc.
Boot = leaking seals, Could affect tank aswell.
Someone mentioned to get a Rare Sares brochure on rust repair sections and check those spots - Absoloutely brilliant advice for the first timer or inexperienced.
I dont think we are being selfish Jim ,Just hard to explain