Originally Posted by rowuk

Clarke had a brilliant approach: soft and slow, work on KKKKKKKK as much as TTTTTTTT.
Many beginners (intermediates, pros) have better luck with gggggggg instead of K and dddddddd instead of T as they are spoken with less force. In theory, that should make no difference, but it practically does.
The fast tongueing required by the Carnival needs a tongue that flows on your airstream. That is why soft and slow are VERY significant in the beginning. If you train your tongue to work like a jackhammer, you will never be able to play quickly. You can train tonguing without the horn too: Ddg Ddg Ddg Ddg............... and alternatively Dgd Dgd Dgd Dgd Dgd....... The first syllable should be LIGHTLY accented. Use a metronome, aim for rhythmic perfection!