As you can imagine the majority of scaffolding accidents occur when planking gives away or slips. We will discuss ways to reduce that risk.
Ensure that you only use scaffold grade planks. Inspect all plank regardless if it's new or used prior to use. If during your inspection you discover any planks that have any type of natural wood defects DO NOT USE.
Make sure your planks won't slip by overlapping the deck by at least 12inches and secure it from moving.
Make sure between the front uprights and guardrail supports that each platform on all levels are correctly planked. The space in between each should be less than one inch.
There are times that your tools or materials will be piled up higher than the top edge of the toe board. In this case you want to make sure you prevent anything from falling to protect anyone whom may be in the line of Fire below. To protect individuals below erect the screening/paneling away from the toe board/platform to the top of the guardrail. This will provide a sufficient amount of distant to reduce any harm to anyone below the scaffold.
Install a guardrail system. Make sure the openings on the guardrail are so small that it prevents falling objects. If there is a chance that a tool can fall and hit someone below that area needs to be barricaded.