Start the metronome at 100 beats per minute. Begin by playing two eighth notes for every beat on a C-major scale to warm up your tongue. Concentrate on maintaining a consistent tonguing stroke and aim for the top of your mouth where your gums hit your teeth.
Continue the exercise using sixteenth notes. This time play one eighth note followed by 10 sixteenth notes and end with a whole note. Do this on each note from "C" chromatically down to "G."
Increase the tempo two beats at a time. Continue to increase the tempo until you can't play the exercise from Step 2 cleanly. Write the fastest tempo you achieved on a piece of paper.
Take a five-minute break and start four beats slower than the tempo you wrote down in Step 3. Attempt to increase your speed on this session by increasing the speed two beats per second until you can't play cleanly anymore. Note your fastest tempo.
Return the next day and start again. Instead of starting at 100 beats per second, start 10 beats slower than your fastest pace from Step 4.