For me, everything I have, except for the 2001 truck, is older. No cars or women under age 18, thank you. No lawn mowers newer than '83, too, except for the commercial grade stuff.

To start, never start a job without looking at a part manual and the service manual. Train your eye to know what the rust / corrosion / wear items you may encounter are. There is no point being only halfway prepaed doing a job - replace the wear items appropriately. Like brake hardware. It's cheap, do it. Anything half decent, save it for the next job.

I start a job in two phases - 1 - disassembly and assessment.
2 - parts sourcing and completing.

I generally get everything I know I will need beforehand, whether locally or not, then make a list of what I might need and where it comes from.

This approach works for me. I have a fleet of Volvos, though, so I usually have a lot of good used and new stuff on hand, though. I can afford to have one down for a week while I work on it. Your results may vary.