How to use these pages
Each letter page does the same four things: it breaks the letter into the strokes it is actually made of, it explains where the letter breaks when you add weight, it names the specific mistake the letter is prone to, and it shows the letters that letter works well beside.
That order matters. The mistake people make most often is jumping to decoration — arrows, drips, extensions — before the skeleton is solid. Every one of those decorations is applied to a stroke, and if the stroke is wrong the decoration cannot save it.
Where to start
If you are learning the alphabet, start with the round family. O, C, U and S teach weight and curvature, which transfer to every other letter. If you already draw comfortably and want to improve, start with the letters you avoid — that is almost always E, S, R and W, and they are difficult for structural reasons that are worth understanding.
Difficulty is about inflation, not about drawing
The difficulty rating on each page measures one specific thing: how hard the letter is to keep readable once the strokes get fat. A letter like I is trivial to draw and easy to inflate. A letter like S is not hard to draw either, and it is the hardest letter in the alphabet to inflate, because it has no straight stroke to hold it together.
That is also why the ratings are not the same as the letters people find hardest to make look good. E scores a four because its three counters close early under weight, which is exactly the problem people run into when a piece collapses in the middle.