Putting a full-motion TV arm into bare plasterboard
An articulating arm multiplies the TV's weight into leverage at a few fixing points, and plastic plugs in gypsum cannot resist it. The mount holds during the demo and fails weeks later. Insist on metal studs, a backing board, or a different wall.
Skipping the building permit and losing the slot
In permit-controlled towers, a technician stopped at security is a wasted visit that you may still be charged for. Five minutes with building management before booking, asking about NOCs, service-lift rules and drilling hours, protects both your slot and your deposit with the building.
Judging the quote instead of the method
The cheapest quote often prices a different job: silicone over silicone, plugs instead of proper anchors, no anti-tip strap on the wardrobe. When quotes differ widely, ask each vendor how they will do the job. The one who mentions wall type, anchors and cure times without prompting is usually the one worth paying.