Here are a few choice excerpts from the 116-page book.
Trust to inspiration for a melody.I believe that his advice is still as relevant for composers of the 21st century as it was for composers of the early 20th century. The analogy Stanford makes about the maker of mosaics holds true for every type of artistic endeavor.
Do not necessarily be satisfied with the form in which it first presents itself, but work at the details while preserving its balance.
When your melody satisfies you, get a bass for it which is as melodious as you can make it without allowing it to overshadow the melody proper. The bass will probably be in your mind as you write the melody.
Practice as much as possible in old rhythmical dance-forms, such as minuets, sarabands, allemandes. Vary the number of bars in your phrases, and be careful to balance them satisfactorily to the ear. Remember that sentences to be intelligible must have commas, semicolons, colons, and full stops, and apply this principle to your music. By doing so you will make your phrases as clear to the listener as they are, even in their cruder form, to yourself.
Found your melodies on the diatonic scale, and treat chromatics as reinforcements and decorations only, until your themes move easily in diatonic intervals.
Study counterpoint first, and through counterpoint master harmony.
Study strict counterpoint only.
Study the pure scale and accustom yourself to think in it. [N.B. The pure scale is an I tempered scale, the kind of scales played on a non-keyboard instrument.]
Practice canonic and fugal writing until the results sound quite easy, natural and musical.
Write always some music in any free style, without thinking about rules, alongside your technical work.
Learn the value of using plenty of rests.
When an artist, who has made a design for mosaic, proceeds to put his picture together, he must make his tesserae so even-edged as to fit easily to each other; if the edges are rough and unfinished, he will not improve the effect of his design by hammering them together and chipping them; nor can he excuse such methods by pleading that the mosaic picture is so far off that no one will see the flaws. The flaws will let in the dust and damp, and the laziness of the inferior workmanship will be exposed by the great enemy of all charlatans, Time.