Breath using your diaphragm. Don't sit slumped over the radio microphone. Sit up straight and breathe in using the stomach muscles. This process is similar to yawning and will enable you to take in enough air to effectively communicate.
Drink plenty of water and tea with honey. The honey will help to coat your throat and provide lubrication for your vocal folds. Staying properly hydrated is essentially to achieving the greatest potential with your voice.
Expand the overall pitch range of your voice by using humming low pitches and singing on the sound "hmm." Start at a comfortable pitch and then gradually lower the pitch until you can't sing any lower comfortably. Then wait one minute and try and go lower. Completed daily, this exercise will lower your vocal range.
Speak at a tempo that listeners can understand. In general, try speaking no more than one word per second on average. Speaking too quickly will make it difficult for people to understand what you are saying. If you are talking about complex concepts, give the listener a moment to let the material sink in, or provide examples to prevent silence on the air.
Exaggerate your mouth and lip movements and make sure you clearly articulate your points. Practicing tongue twisters such as "Sister Susie Sat on a Second Thistle" will greatly help improve your articulation.
Listen to recordings of your voice. You can only change your voice if you know what it sounds like. By listening, you can decide if you need to slow down, speed up, speak more clearly, take a bigger breath or change the pitch of your voice.