For me, the building blocks of technique are scales. Major scales, all three forms of minor scales (natural, harmonic, and melodic), diminished scales, and whole tone scales. There are lots of variations here (modes, blues, be-bop, etc.) but for the sake of this discussion, we will focus only on major, minor, diminished and whole tone.
As always, place your metronome and tuner on your music stand in front of you and turn them on. Set the metronome on a reasonable tempo - somewhere between 60 and 80bpm and start with C major in the middle of the horn. Play the C major scale from middle C all the way up to high F, then all the way down to low B, and then back up to middle C using 1/8th notes as the rhythm. Be sure to play with a full, even tone and in addition to playing exactly in time, make sure that you are centering the pitch of each note, using the tuner as your guide. Don't worry about doing the entire scale on one breath. When you are near the end of your breath, simply stop, take a big breath and then begin again on the next beat. The point of the exercise is not to play the whole scale on one breath, the point is to play the entire range of the instrument in time and in tune and at a tempo that allows you to remain in control for the entire scale.
Repeat this for every major scale, playing to the top of the horn, back to the bottom of the horn, and returning to the starting note in the middle of the horn. Depending on what key you are in, the top note and the bottom note of the exercise will vary and that's OK. For example, the top note of the exercise in C major is F and the bottom is B. The top note of the exercise in B major would be either E or F# (depending on whether or not you have a high F# key on your horn), and the bottom note would be low A# (or Bb). Again, the point is to play the full range of the instrument (no altissimo) within the key that you've chosen. Make sure you are honest with yourself and do not proceed to the next scale until you have played the one you are working on perfectly. Take extra care to play exactly in time, in tune and with expression. When you have completed all 12 perfectly, go ahead and increase the tempo a few bpm and repeat. Please do not rush to get to a fast tempo - you then defeat the purpose of the exercise. You must be methodical and you must be honest with yourself. Making mistakes means you are giving yourself a chance to improve!
I usually tell the story of the great cellist Yo-Yo Ma who would set up 5 matchsticks and when he played a passage he was working on perfectly, he would take away one matchstick. He would then play the passage again and if he played it perfectly, the 2nd matchstick would be removed. Played perfectly a third time in a row, and the third matchstick would be gone. Played perfectly on the 4th try, the 4th matchstick disappears. One mistake on the 5th try and all 5 matchsticks return to their starting position. Practice does not make perfect. Perfect practice makes perfect.
Once you've done this for all your major scales, repeat in the same fashion for all of your minor scales (natural, harmonic, and melodic) as well as your diminished and whole tone scales. I would advise focusing your efforts on only one of these options per practice session I.E. only major scales or only harmonic minor scales or only diminished scales, etc. This way, you can really focus on that tone color and master those sets of scales.
I cannot emphasize enough the need to master all of your major, minor, diminished and whole tone scales. They are the building blocks of all Western music, regardless of your preferred style. This exercise, of course, is just one of many when it comes to practicing scales and in future blog posts, I'll share some of my personal favorites.