I think the most important part of writing good documentation is being descriptive in your steps. If someone reading a particular piece of documentation is left confused about where something is or how to access it, then that means there may be something missing from the documentation that should be included.
My project already has some amount of documentation, but so far that has really amounted to detailing the steps we have taken so far in gathering resources for the archive. Now that we have been zoning in on potential solutions, and I’ve been moving to testing websites, I’ve been thinking about what to document. Both Omeka and CollectionBuilder require certain steps with setting up spaces for images, and with the amount of content the theater department has, I have to consider the quickest ways to get the content organized both before it is added to the website and once it is already visible. This would most likely look like creating detailed steps for organizing test spreadsheets and setting up website pages once I figure those things out myself.