A few of the magic rules with tailor's shears and scissors.

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If you have spent reasonable sums of money buying good shears, the last thing you want is for someone to use them for any other purpose.
They generally will not know the difference after cutting plastic, rubber of hard cardboard but you certainly will as the drag fabric down between the blades and don't cut properly.

• Never ever cut anything other than fabric with your good shears. If you must cut plastic, pattern board or sheet rubber, use another cheaper pair.
• Don't let anyone else use them, they will cut things that make the blades blunt or worse.
• Give you shears or scissors a surprise, actually oil the hinge. Grease works better but anything is better than nothing.
• If they are of the type that can be pulled apart, learn how to adjust the hinge to get the optimum adjustment.
• Unless they are made of stainless steel, keep them oiled when not in use so they don't go rusty.
• If they are a large and heavy pair of shears, never even drop them on the floor, their weight risks damaging the hinge and blades.

Most shears come with a story. I bought a pair of 13 inch Wiss shears from an elderly lady in western Sydney and while dealing with her son to arrange payment and shipping, he told me he remember what they sounded like as his mum cut out a wide variety of garments while he was still a kid.
None of her kids were ever allowed to touch them as she bought them in the early 1960s at some weeks wages as an apprentice. I eventually passed them after restoration to an elderly trouser cutter as I personally restore the older brass hinge type.