IT-Documentation needs to be consistent and central
This is the most important mantra to always repeat when writing your documentation.
1. Define a level of information depth. When you document one piece of information for a single item (e.g. an IP-address of a server), you should document it for all other items as well (all IP-addresses of all servers).
What happens if you don’t? Documentation isn’t just for you, it’s for all the people you are working with. People rely on the information and expect it to be complete. If your coworker finds the IP-address of server A in the documentation, he expects the IP-address of server B also to be documented. If it’s not, he loses trust in the documentation. See “IT-Documentation starts with politics”. Set yourself small goals and try to reach them step-by-step. Yes, it is enough to just document the IP-address and hostname of all servers as a first step – as long as you cover all servers completely.
2. Documentation needs to be up-to-date. If you don’t update the IP-address of a server in the documentation, the same thing applies as in point A: Your coworker finds out it’s the wrong IP and loses trust.
3. Documentation has to follow guidelines. If you describe your printers as “HP Printer X” and the helpdesk guy documents them as “Hewlett-Packard printer X”, you will have a hard time reporting data about your printers. Set some rules for naming schemes!
4. Documentation needs to be placed in one central place. Documentation comes in different shapes and sizes and if your platform can’t handle some files or graphics, just link it. You don’t need .ISO backup files in your Wiki, but you need a link to the place where these files can be found.