As beginning players form the skills necessary to play brass instruments, they can get into a range of bad habits, that if go unfixed, can lead to serious playing problems later in their career. It is important to correct these minor problems as they start, as they are much harder to break once they have been practice and are ingrained into muscle memory.
Poor Breathing and Posture
Beginning students should learn to breath correctly before they even play a note, but the topic is often overlooked by teachers and learn-to-play books. Proper breaths come from the lower gut, not the chest. It takes practice, just like every other aspect of playing, and should be practiced both in musical contexts and separate from the horn.
Posture and breathing are very closely related. Sitting perfectly upright opens your air passage completely, which is necessary for proper breathing.
Incorrectly Holding the Instrument
The way a player holds their horn can greatly affect how their technical ability develops. Trumpet players will find their fingers working much faster when they push valves with the tips of their fingers rather than the middle.
Similarly, for trombone players, incorrectly holding a trombone slide will slow you down and make you less accurate. The use or misuse of the wrist can also make someone trip up when sliding quickly between close positions.
Not Considering Tone While Playing
Beginning brass players have a lot to think about. Even in a single note, they are thinking about their breathing, embouchure, fingering or slide position, articulation, and dynamic level. Tone, or the actual quality of the sound that is produced is often overlooked in the midst of all of this, and is maybe the most important thing of them all. Is a wrong note that sounds good really a wrong note after all?
This is most often shown in practicing theory or technical topics. For instance, many beginning players, when practice their scales, will get every note right, but ignore their embouchure and breathing. This can produce an airy or harsh sound, and be very unpleasant.
Practicing musically, or looking at everything as a piece of music, not just a scale or etude will help them produce a great tone every time they play. Even the most repetitive etudes can sound like beautiful pieces of music if good tone and emotion are used.
by Kyle M. Bagley, http://www.kylembagley.com