Probably all very old news, but you all seem stand up guys...
Secret nailing through the face of a board? Lift a shave with a 1/4 chisel but don't break it off. Nail through the cut part, punch the head and glue the lifted shaving back down with a high tack adhesive (yellow glue, fish glue). A light sand, and nobody will ever know.
Nailing the end of a board and don't want it to split? Blunt the point of the nail with your hammer.
Make sandpaper go further when not using a block: fold into four, tear along ONE of the folds, fold it back into quarters. When one face wears out, refold to get a new face.
So you marred the face of your expensive timber on that stray screw/ piece of gone off glue on your bench? Put a damp towel over the ding and apply a hot iron. Sand back with 320.
You're screwing into end grain chipboard and you just *know* it's going to split out? Drill the "receiving" piece to accept a wall plug as a snug fit. Screw into the plug. Go slow, let it bite, tighten carefully.
Yeah, we knew all that. But it might save somebody some heartache.