Tip for hogged out screw holes on trim or interior
I don't know if this is a common trick or not, but I just stumbled onto it. I was replacing the front wheel well trim on my '69 Malibu and once I got it off I saw a bunch of green rubber material in the screw holes. Turns out it was snips of electrical wire. It soon became clear why: the holes in the fender were either too big from the factory for the stock screws or hogged out over the years. The previous owner had cut 1/2" pieces of electrical wire and stuffed them in there, giving the screw something to bite into and tighten. This had held the wheel well trim for at least 15 years. The principle is sound; I've done similar with toothpicks and wood glue when repairing furniture.
The holes in the fender of my car were too big even for oversize screws to tighten completely, and those screws, even though they'd be kind of out of the way, looked out of place. I tried the electrical wire and it worked great. For the holes facing down, I cut the snips to be about 1" long and bent the tip down like a hockey stick and stuck the long end in there to keep it from falling out. Some of the screws bit mostly into the rubber and tightened down just enough, but some apparently bit into the wire and tightened down as tight they would have into metal holes.
I wouldn't use this trick for anything structural or under stress, but it's great for trim or interior pieces where oversize or non-factory screws would look garish.
By the way, I wound't be upset if someone "hijacked" this thread with unrelated but equally helpful tips or tricks.