When adding a new project:
Demonstrate a single feature
Keep your assets as small as possible
Save the project into a directory with the same name as the main blend file (/.blend)
Prefix the name of the project with the category the of the showcase (logic_, light_, render_, ui_, ...)
Add a /README.md describing the project
If the README.md includes usage instructions (like: keybindings) link it as text file into blenders Text Editor.
Remove any orphaned data from your blend file