These articles show some varied approaches to making graphic scores or other forms of alternative notation:

• Some look exactly like standard music notation BUT with one or a few changes (like bending the staff into a circle);
• Some use musical symbols—or things that resemble them—but warp them such that it leaves the realm of “tell me what buttons to push, and when” and focuses on communicating more subtle and complex things like affect or relationships between the things played (and the exact things played might be left open for the performer to interpret);
• Some may look like graphs of pitch over time, with precise measurements or just rough indications of overall shape
• Some may just consist of verbal directions or prompts for meditation
• Some may not be linear, left-to-right: they may be curved or nonlinear, even laid out like a board game

Links:

• Ligeti, Artikulation (1958) with score.
• Classic FM, “Art and music collide in these 20 stunning graphic scores”
• The Guardian, “Graphic music scores – in pictures”
• Graphic Score Explorations—several newly commissioned graphic scores, with recordings
• A YouTube playlist with graphic scores and performances from the 2013 Open Form Festival.
• Creative Review, “How the Toronto Symphony Orchestra uses graphic design to guide audiences“