Top 4 Exercises To Improve Your Diction.

Having good diction means enunciating/pronouncing your words clearly. Strong public speakers work on their diction to ensure listeners can follow their meaning and miscommunication is avoided. (Consider how the word winter is often pronounced as winner, or how library is often pronounced as lie-berry.)

These top 4 exercises will help you improve your diction:
Tongue twisters: Not just a party game. There are hundreds of examples available; find five that focus on your weak areas and practice saying them. Work on each until you have mastered it, and then move on to another. 
Read passages aloud: Select excerpts from a book you are reading or a poem you enjoy, and practice reading them aloud. Focus on effective breathing and slow down your normal pace as you focus on enunciating each word.
Loosen your jaw muscles: Again, there are countless exercises to work both your tongue and jaw. Select 2 or 3 and practice them every morning.
Speak around a cork: Take a wine cork and place it between your front teeth. Take a good, deep breath, and then try to speak as clearly as possible. Do not bite on the cork or clench your teeth.

Find a combination of these exercises that work for you and your schedule. Aim to practice them each day, and I guarantee you will hear your diction improve.