5 minutes of warm-up exercises before a session dramatically improves articulation and delivery.
Relax your lips completely.
Press your lips firmly together.
Open your mouth as wide as comfortably possible.
Extend your tongue as far out as possible, pointing it downward.
Fill your cheeks with air like a balloon.
Close your mouth and hum at a comfortable low pitch.
Make a 'wee' sound and slide from your lowest to highest pitch.
Breathe IN through your nose for 4 counts.