Enlarging music
One of the simplest ways to make music easier to read is simply to make it larger. Of course, when viewing music on the computer screen, you can change the zoom level to make the music as large as you like, but when you print it out this doesn’t work. Rather than blow things up on a photocopier, you can simply use the Staff size control in Layout > Document Setup to make the music as large as you like.

When changing the size of the music, you may also need to change the distance between staves and systems to make things as clear as possible. The quickest way to do that is to select the whole score (Ctrl+A on Windows or Command-A on Mac), choose Layout > Reset Space Above Staff and Reset Space Below Staff to remove any existing vertical spacing overrides, then choose House Style > Engraving Rules, go to the Staves page, and change the spaces between staves and spaces between systems values.