Players should above all bring the horn to their face in the place where it feels natural, without changing or contorting their basic body position.

Posture certainly impacts comfort and tone production on the horn. Poor overall posture can create all sorts of problems, while good posture promotes free breathing and better performance. As a basic rule, I suggest a relaxed but fairly upright posture, just barely leaning back at the back of a typical chair. An even better posture would be to have your body slightly more upright and at the point where you "balance" - where you are not leaning forward or backwards - sitting either at the back of the chair or somewhat out on the chair.

The best posture for playing the horn seated is closely related to a relaxed standing posture. Players should above all bring the horn to their face in the place where it feels natural, without changing or contorting their basic body position. Many horn players at the late high school and college level (and even professional horn players) have serious posture issues that relate to individual growth (perhaps they were smaller when they started playing the horn) and old habits. It is wise for every horn player to keep reevaluating posture periodically, or, before you know it, one might end up with a posture that inserts unnecessary tension in your body and as a result, in tone production.

Another element that can generate poor posture in a horn player is an uncomfortably placed little finger hook in relation to the valve paddles. Especially on student model horns it is common to find that this hook is placed in a location that, while perhaps aesthetically pleasing, literally no human could possibly find comfortable. Not only is the horn difficult to hold, which will have a negative impact on posture (and desire to practice), but also the uncomfortable hook location can easily lead to problems in the left hand and arm. Fortunately, it is a very simple matter for a competent brass instrument repairman to move this hook to a comfortable location tailored to the individual hand.

A "duck’s foot," "flipper," or hand strap may be of great help with support of the horn, especially in relation to holding the instrument off your leg if needed or desired. Some players shy away from these devices, fearing that they will cause one to use more pressure in the high range, but the fact is these devices primarily make the horn more ergonomic to hold, resulting in a more balanced way to cope with an instrument that is inherently awkward to position, whether seated or standing.

Depending on your height, good posture may require considering playing with the bell off the leg. Many horn players lean down and slouch to play; while the position may seem "natural" and normal, this type of position cuts lung capacity, crimps the neck, and tends to lead to extra tension and problems in the left arm. So again, it is always a good idea to re-evaluate posture periodically.