There’s lots more stuff you could include. For example:

• indication of which part of the hammer should be used to strike the nail
• recommended angle of entry for the nail to penetrate the wood
• recommended angle of impact for the hammer against the head (once correct part of hammer is indicated)
• scale: how long/thick is the nail? How thick/deep is the piece of wood? Is the illustration to actual scale, or is it a more general representation of the objects?
• material composition of nail
• type and density of wood
• grain direction of wood
• is the diagram indicating relative positioning, or absolute? For example, does the wood always need to be parallel to the ground, and does the nail always need to be perpendicular to the ground.
• description of variances with respect to types of nail heads; some may have squared edges, others may be beveled.

I could keep going, you get the idea.