Aside from your specific maintenance regimen, there's really no prescribed plan other than really knowing your vehicles (to include common failure points) and simply making routine inspections at more frequent intervals than one would conduct with a newer car.
As an example, most 1980s Chrysler vehicles suffer from worn/deteriorated wiper arm bushings. Discovering this during a rainstorm is obviously not optimal. They should be checked every few years and changed as required.
Most Chrysler timing belts have specified change intervals. They have to be checked every few years and should be preemptively replaced. Break the belt and you're dead in the water. Don't let it happen.
Many early 2000s vehicles eventually pop a P0456 code for "very small EVAP leak." Owning a 20-dollar smoke machine will help you pinpoint the leak(s) and get that annoying check engine light to switch off.
Almost every old car will eventually suffer from crispy-crittered vacuum lines and electrical wiring...especially when subjected to under-hood heat. Have to check these items frequently and have spares handy.
Checks include frequent looks at everything under the hood and rolling under the vehicle to make inspections more often to check things like steering and suspension components, checking the water pump weep hole, CV joints and boots, etc.
The best prevention is to know your car well and address issues before they arise.
Another strategy I have is maintaining bench stock of high-wear and other items. I have ample supply of pads, rotors, brake hardware, belts/hoses, and even an extra radiator and two fuel pumps. I got most of this stuff from swap meets, ebay, and the Rock Auto closeout section for pennies on the dollar.
My stash came in very handy last month when my '86 Daytona wouldn't start after we visited a local restaurant. When I turned the ignition to the "on" position there was no audible buzz from the fuel pump (it's usually very noticeable). I decided to use AAA to get it home (free tow at 7 miles), and sure enough that 40-year-old fuel pump had up & died.
Dropped the tank, grabbed a new Carter pump (paid a bit over $8.00 for it) from my attic, and went to town. Since the tank was out of the car, it was a great time to clean and repaint that tank, change all the fuel injection hose (from my big rolls of 1/4" and 5/16" fuel line), change the filter, and install a new filler neck grommet. Was all done by late afternoon (mainly to let the paint dry) and was back in business.
Although we primarily use the Daytona for local errands, I would not hesitate to take her on a road trip.
In short, there's no magic bullet. Folks who know their cars know what they're doing and make regular inspections almost unconsciously. It's almost one of those "If I have to explain it to you..." situations. Car guys just know what to do.
