1. Narrow the tongue and place it against your upper gum ridge. Make sure the sides of the tongue touch the sides of the upper molars. Lower your jaw slightly, keeping your teeth apart.
2. Hold your tongue firmly in place against the gum ridge. Force some air from your lungs and allow pressure to build up behind your tongue. Let the air pressure overcome your tongue and force it away from the gum ridge. Add voice. Try to time your voicing so that it begins at exactly the same time that your tongue starts to leave the gum ridge.