Tonguing is so important for trumpet playing. It helps define our sound. Here are five points about single tonguing with recommended exercises:

1. Response. You may not think of response as important to tonguing, but if your lips don’t respond right away to the airflow, then your tonguing will be out sync and sound clunky. Practice starting notes with a soft air attack. Focus on a small embouchure by thinking “pooh.”
2. Stability of the tongue while articulating. You want the middle and back of the tongue to be relatively still when tonguing. To work on this, focus on the sides of the tongue touching the inside of the upper molars (this makes a tunnel for the air stream, and is normal). While focusing on this connection, you will be able to tell if the middle or back of the tongue is moving. Give yourself a gentle reminder to not move these parts much while you do the normal single tongue articulation.
3. Synchronization between the air and tongue. Remedy: “pooh” attack, rest, then a regular tongued attack, checking that the tongue is timed exactly with the air. The most common mistake is to tongue before the air. You can also try breath attacks followed directly in the same airstream by a tongue attack. Repeat many times, with the tongue attack happening closer to the breath attach on each repetition until they coincide.
4. Too much tension in attack. This sounds overly crisp or clumsy. Try to articulate more legato. For staccato, try to achieve some of the shortness by releasing the air quicker, rather than tonguing too hard. For an accent, try focusing on an increase of air as the articulation is happening. The air is the primary control of volume, and an accent is defined by the extra burst of volume at the attack.
5. Speed. Work on a steady stream of 16th-notes for a minute at a time, starting with a relatively slow metronome speed (like 70 bpm). Focus on fluid tonguing that bounces off of the air. Increase speed as long as the tongue remains relaxed. Make this a daily exercise.