One principle has served me well ever since it first dawned: Tools are not holy relics.
Three examples of what follows from this enlightenment:
1) Worn out, broken, unsuitable, or unsafe tools should be discarded or destroyed immediately and with extreme prejudice. It's never worth it in terms of time wasted, parts ruined, and risks to life and limb to put up with bad tools. The instant a Phillips screwdriver displeases me, it now goes into the trash or recycling. All those crappy old K-Mart wrenches made of butter and sawdust were tossed into the trash years ago (I refused to contaminate the metal recycling bin). When my jack started leaking down, I immediately bought another rather than risking my life trying to limp through one more project.
2) Tools can and should be freely modified in order to accomplish needed tasks. For example, I keep a few reasonable quality 8mm and 10mm wrenches on hand as raw material for cutting and bending into specialty wrenches for reaching fasteners in weird places.
3) Extreme brand loyalty is silly. There are good and bad tools of every brand and made in every country. Judge each tool on how well it does what it does for you, not on how pretty it looks sitting in a drawer being useless, or where it was made. Obviously, there are tendencies; some brands and countries tend to make better or worse tools. But there aren't a lot of absolutes.