The Norton Manual of Music Notation

The ability to read and sight-read music effectively depends on a lot of factors. The symbols on the page are extremely important, of course, but there are a lot of subtle elements that can help clue us in on what's going on when we don't have time to process each symbol individually. Spacing is a big one. A lot of computer-generated scores that I've seen online have poor spacing and it makes them more difficult to read than they should be.

The Norton Manual of Music Notation is a great book on how to write music properly and quickly.  Although its focus is on hand-written music, its principals apply to any western music notation. I recommend all musicians learn to recognize and apply these ideas, through this book or other similar ones, in order to make sure we have quality written input for our music making.