One of the most fundamental mistakes is diving into the installation process without a comprehensive plan. Proper planning involves assessing the layout of the workspace, determining the cable routes, identifying the types of cables needed, and considering future expansion requirements. Skipping this crucial step can lead to haphazard installations, inefficient cable management, and difficulties in troubleshooting down the line. Each networking standard has specific limitations on cable length to maintain signal integrity. It's essential to adhere to these guidelines to prevent signal degradation, data loss, and network disruptions.