The goal is to achieve legible writing. Because most writing is done with lower case letters , not capitals, mastery of the lower case letters, first, is essential. Several capitals are basically enlargements of their lower case counter-part.
The writer must be consistent in the letters' slant, size, shape and in the spacing of words and letters. The slant can be either to the right or left. The most typical slant is to the right. Tall letters are uniformly made the same height and the mic-line letters also conform to the same mid-line height. The shape of letters can be oval or rounded but not mixed.
The spacing of letters and words is even and not squished together.
Another D'Nealian Handwriting tip is to not worry about speed. This will develop naturally as the beginning writer develops confidence in this skill.
Remembering these four words - all beginning with the letter "s", will help you to produce clearly written penmanship: Slant Size Shape and Spacing.