The Occupational Safety and Health Administration (OSHA) encourages retail employers to take precautions to prevent worker injuries during Black Friday and other major sales events. Here are some pre-event setup tips from OSHA:

• Set up barricades or rope lines for crowd management well in advance of customers arriving at the store.
• Make sure that barricades are set up so that the customers' line does not start right at the entrance to the store. This will allow for orderly crowd management entry and make it possible to divide crowds into small groups for the purpose of controlling entrance.
• Ensure that barricade lines have an adequate number of breaks and turns at regular intervals to reduce the risk of customers pushing from the rear and possibly crushing others, including workers.
• Designate workers to explain approach and entrance procedures to the arriving public, and direct them to lines or entrances.
• Make sure that outside personnel have radios or some other way to communicate with personnel inside the store and emergency responders.
• Consider using mechanisms such as numbered wristbands or tickets to provide the earlier-arriving customers with first access to sale items.
• Consider using an Internet lottery for "hot" items.
• Keep shopping carts and other potential obstacles or projectiles inside the store and away from the entrance — not in the parking lot.
• If appropriate, provide public amenities including toilets, washbasins, water, and shelter.
• Communicate updated information to customers waiting in line. Distribute pamphlets showing the location of entrances, exits, and location of special sales items within the store.
• Shortly before opening, remind waiting crowds of the entrance process (i.e., limiting entry to small groups, redemption of numbered tickets, etc.).

Source: OSHA Fact Sheet: Crowd Management Safety Guidelines for Retailers, http://www.osha.gov/OshDoc/data_General_Facts/Crowd_Control.html.