It should look right when it's written with a ballpoint pen, a pencil, a crayon. In our time, the broad-edge pen is a charming exception. It should have simple capitals of classical proportions. The model should be a foundation, not an end in itself. Italic will never suit everybody.
Some people like to write zigzags, others prefer loops.
Young people want to develop their own handwriting. Even when they affect an illegible scrawl, their hand will still know how to write. A handwriting model should have simple capitals of classical proportions. In comparison, words in capitals of most copperplate-based hands look illegible and silly. These are excellent aims, to be sure.