When I work in the shop I keep telling myself "when in doubt, clean up." Between jobs? Clean up.
Perplexed about the work you are doing? Ponder while cleaning up.
Etc.

Around Volvos: when in doubt, clean up!
1. Grounding points
2. Connections

1. If you clean the grounding points (see books by Bentley or Haynes, or Brickboard FAQs) and then slather them with oxygen-restricting pastes (e.g. OxGard; again, see this site's FAQs) your car is ready for another zillion miles and bunches of years. (This is following Sec. Rumsfeld's lead, trying to know what you know, where before you didn't know what you didn't know... or maybe you DID know that you didn't know, and were irritated; yeah, whatever.)

2. Clean and reseat connections, especially, of course, those that figure in spark and fuel. (Audio and bun warmers and such are far down the list, right?). For instance, I have been puttering with an unfamiliar 240 recently, and ever eyeing the 8-lead connector, which handles most essential tasks, and sits dead behind the engine, asking "Are you up to it?"

Clean the area. Reveal suspects. Ease your work. Then keep it clean.
It's like a diet. Taking off the pounds looks intimidating. If you can do that, maintenance should thereafter simply be maintenance; knock on wood. :-)
--
Gregg; Mpls, MN; 1987 745, 1967 Amazon 4-dr.