Looking through an old scrappy magazine tonight, I thought of this topic. "Useless" is subjective so we may all learn a thing or two with this thread!
Anyway, the most useless tip I read was putting painter's tape on stamps to ensure not getting ink on stamps. To me, that is a waste of time. So what if my stamps get a bit of ink on them? If I am careful when using them, I should be fine anyway, and surrounding the image with painters tape is time consuming.