Vacuum properly, not constantly
Slow passes matter more than frequent ones. Vacuum both sides a couple of times a year, and keep beater bars away from fringes, which they shred.
Rotate and use a pad
Rotating once or twice a year spreads traffic and sun exposure. A pad cushions the rug against the floor, reduces abrasion and stops slipping.
Deal with spills in the first minutes
Blot from the outside in with a clean white cloth. Avoid supermarket spot removers on wool and hand-knotted rugs, and tell your cleaner what you used, because that changes what they can do.
Pets
Urine soaks into the backing and the floor beneath, so surface cleaning leaves the smell behind. Treat accidents quickly and tell the cleaner where they happened, even if they are invisible when dry.
City dust and radiators
New York apartments collect fine soot and dust, and radiators bake it into fibers. Keep rugs a little away from radiators, and air rooms when you can.