Forget all these practicing sheets
Hand-lettering is often mistaken as calligraphy. But while lettering is about drawing or illustrating letters, calligraphy is about appealingly writing those letters. This "appealing way" is neither defined nor are there standard rules for calligraphy. What you must know is that this popular style in which the letters are written in these hundreds of "practicing sheets" we all know is entirely fictional. And now everybody does "brush lettering" exactly the same way.