Read it through once

[2] I earnestly recommend those who desire to study this Art to begin by daily practice in the description of things, even common things, that they have observed, by reporting conversations, and by word-portraits of their friends. They will find that the practice gives them firmness of outline, quickness of observation, power of catching important details, and, as regards dialogue, readiness to see what is unimportant. Preliminary practice and study of this kind will also lead to the saving of a vast quantity of valuable material, which is only wasted by being prematurely worked up into a novel written before the elements of the Art have been acquired.