Third week
The Instrument 
You are about to insert your mouthpiece into your instrument and produce your first notes as opposed to the sounds you have been making up to this point. Congratulations! But, first what do you know about this instrument of yours? While even a fine pianist needs know little or nothing about the mechanism, maintenance, tuning, etc. of the piano, it is important for you as a brass player to know your instrument, know hove to care for and keep up the working parts, know how to tune it, and know the principles governing its operation.
(Embouchure  training, page 40,Prelude to Brass Playing)

Instrument Practice
You will do well to regard your instrument as an amplifier a loudspeaker that amplifies the sounds made by your lips. You are aware by now that there is nothing magical about valves or trombone slide. They merely make more notes available to you. It is for you to make your lips vibrate at the frequency for the notes desired. In other words, you depend on the lips. The action of moving the valves or slide may be reckoned as only about two percent in importance.
(Embouchure  training, page 55,Prelude to Brass Playing)