Find the wall studs with an electronic stud finder. Mark the locations with a pencil. You must mount the shelf standard directly to the wall studs for it to hold 200 pounds, regardless of the hardware you use.
Purchase a shelf standard and bracket system rated for the capacity you need. The shelf standard will be installed vertically, with the brackets installed horizontally and perpendicular from the wall. Look for a weight capacity rating of 200-plus pounds.
Mark the location for your pilot holes along each wall stud where the shelf standard will be mounted. Assume you will need to anchor each standard in at least three different locations or as many as the manufacturer recommends to reach the 200-pound weight capacity. A shelf standard should be installed at each wall stud location to support heavy loads.
Drill the pilot holes. Use a depth accommodating the screws that came with the shelf standard and bracket system. Only use the screws provided by the manufacturer. Other hardware might not be rated for a 200-pound capacity.
Place each vertical shelf standard along the wall studs. Install the screws through the holes in the standard and into the pilot holes using your power drill and the appropriate screwdriver bit. Install the rest of the shelf standards the same way.
Hook on the shelf brackets. The brackets should be at the same level on each shelf standard. Place a level across the brackets to ensure they're even.
Cut the shelf. Use hardwood, rather than plywood, for stronger shelving. The shelf should hang over each end bracket by 1 to 2 inches and should not hang over the front by more than1/2 inch. Use a circular saw to make the cuts and sand smooth.
Place the shelf across the brackets. Finish building the shelf by installing screws through the bottom of the brackets and into the hardwood shelf. Use only the shelf manufacturer's screws to ensure you get the full weight capacity.