Inhale into the diaphragm by expanding the diaphragm muscles. The act of expanding the muscles of your stomach will automatically pull air into the lungs. When your lungs are full, your sides should feel tight and your stomach should expand.
Push air out of the diaphragm by keeping your stomach muscles tensed and controlling the airflow. Keep your tongue slightly elevated to create a faster air stream, which will aid you in improving your tone.
Play a series of long tones. Start on G, with open valves, and descend to F-sharp, middle valve, and then return to G. Hold each note for four beats. Take a quick breath and play the series a half step lower. This time from G to F, with first valve, and then back to G. Hold the tone as steady as possible to develop your embouchure strength.
Practice lip slurs on each valve to improve your flexibility and ability to move from one octave to the next. Start on open valve G and ascend to the next partial, then return to the original starting note. Then slur up to the second partial, slur down to the first partial and back to G. Continue this slur on all seven valve combinations: open, middle, first, the first two valves, second and third valves, one and three and finally ending on all three valves.