Place your tongue tip on the ridge behind your upper front teeth.
Start the buzz before you release: hand on throat, feel the hum while the tongue is still touching.
Release softly, with no strong puff of air.
For a final /d/, hold the buzz right to the end of the word.
Now say: did, odd, red.
✅ Check
Say "to" and "do" with a hand on your throat. /d/ buzzes from the first moment; /t/ does not. Then check endings: "bad" must not collapse into "bat".
⚠️ Common trap
Devoicing at the end of a word. If the buzz dies early, "red" sounds like "ret" and listeners hear the wrong word. Keep your vocal cords humming through the final /d/.