I find the line spacing wastes a lot of space, particularly when printing. This post describes a way of changing the line spacing in the editor, but it isn't detailed enough for me to follow, and it doesn't sound as though it would apply to printouts.
How can I reduce the whitespace between lines in printouts?
For example if I wanted to alter the rendered output with slightly smaller list bottom margins:
Help > Open Profile directory
Open userstyle.css
Add the following to the file
li {
margin-bottom: .2em !important;
}
(default is .4em)
Restart Joplin (as in fully, by default it probably just goes to the system tray so you need to kill it there too).
If that doesn't do what you want then lower it further or look into changing the line-height property (you can make it global or just on the li style (list item).