I think a good online guide is:

• Easy to follow
• A mix of text and images
• Is accessible and conforming to W3C standards

More specifically, this means:

• Easy to follow
  • Each process is described by a list of steps. Processes may be broken down into sub-processes if needed.
  • Written in second person, active voice.
  • Use a numbered list, with each item a step in the process.
  • Be specific (removing ambiguity)
  • Keep any explanation to an overview of the process.
  • Bold any references to specific labels that can be seen on-screen.
• Text and images
  • Images (including screen shots) are saved in full resolution into a Teams folder.
  • A placeholder with the image name is placed after the image (enclosed in square brackets). This provides a placeholder when the text is cut and pasted to the web.
• Accessible
  • Conforms to a simple hierarchy of information (no more than 3 levels deep in one guide)
  • Text is at least 12pt and in a sans serif font (and use this Charlie Mac template as a starting point)
  • High contrast between text and background (preferably black text on white background).
  • Don't use tables or other structural elements to organise text and images.