Playing the marching baritone is very similar to playing a trumpet. The marching baritone and the concert baritone both have the same fingerings and use the same mouthpiece, so you will not have to learn an entirely new instrument. In fact, the only element that changes from the marching to concert baritone is the method of holding the instrument. The marching baritone extends directly out in front of you and possesses a key ring that you use to add extra support.
Wrap your right hand around the marching baritone valves, with your thumb extending around the lead pipe by the first valve and your small finger placed inside the pinky ring toward the end of the third valve.
Place your left hand around the left side of the marching baritone valve casing. The side of your left thumb will touch the tip of your right thumb. Your index, middle and ring fingers will wrap around the third valve.
Stand at attention by holding the marching baritone with the bell down and directly out in front of your body. Avoid the tendency to rest the baritone on your chest. Build the strength to hold the instrument out properly.
Bring the marching baritone to playing position by twisting both of your hands at a 90-degree counter-clockwise angle. The bell should be facing slightly up at this point.
Play the marching baritone using the same embouchure you would use for the concert baritone. Keep a tight embouchure by mimicking the motion of sucking through a straw with your cheeks firm.
Breathe into the diaphragm; pretending to yawn can do this. Expel the air by using your stomach muscles to push the air out of your body.