Yesterday, I had a nice discussion with Mark on how to build effective building instructions. I am a great fan of LEGO bricks and I am used to read their building instructions that represents the model in a three-dimensional perspective and show at each step the parts that need to be included.
Mark was highlighting that instructions should prevent user’s mistakes before they arise. Many times it happened to me that a wrong interpretation of the drawing brought me to a mistakes that had consequences and was detected only a couple of steps afterwards. Then the way to fix is to go back those steps and try again. However, this is something possible with LEGO bricks. When the building parts are made of wood and iron then a mistake can have permanent consequences. In these cases, preventing a mistake is even more important.
IKEA does a great work in designing readable building instructions for their furniture elements. I remember spotting many times details added to prevent mistakes. In the example below, the user is cautioned to align the two parts in such a way that the right hole is filled with the metallic screw.
More examples here.