Stuttering is, among other things, associated with breathing irregularities. Scientists researching the disorder found out that a stuttering person sometimes stops breathing completely or starts breathing in a wrong way, eg inhaling while speaking instead of exhaling. Therefore, creating proper, for some people new, breathing habits may become the first step to getting rid of stuttering and regaining fluency of speech.
There are some simple breathing exercises that can help you relax your body, put your mind at ease, and get your message through in undisturbed manner. The first thing to do is to observe yourself. How do you breathe? Do you take deep breaths using your diaphragm (you can tell this by observing your belly movement; if your belly moves forward when you inhale the air, you use your diaphragm; if not – you use only your chest muscles to breathe). If no, this is the first step to learn. Again, you can find many materials relating proper breathing on the Internet, and you can also consult your physician.
What is the pace of your breathing? Do you usually breathe slowly, so taking deep breaths providing your body with more oxygen? If your breath is fast and shallow, you might want to start controlling it as you learn to breathe in a proper way. Quick and shallow breaths invoke quick and nervous speech, and this usually leads to stuttering.
There is one interesting and effective exercise that I would recommend. It is aimed at regaining regular and natural breathing during speaking. It is best done with a partner, as it requires someone you can talk to. Ask your partner to ask you questions, reply to what you say, so that you can have a regular conversation. When it is your turn to speak, take a deep breath, inhale the air, say one word while exhaling, inhale, say one word while exhaling, and so on until you finish the sentence. Next time try to say two words on one breath. Then three, four, until you can say one full sentence on one breath.
Another exercise consists on making a list of words difficult to you, and learning to say them correctly. You breathe like in the first exercise, but this time you divide the word into syllables. Take a deep breath, say the first syllable, breath, second syllable … When you master this, try to say two syllables on one breath, then three, then the whole word.
These are simple exercises, but very effective ones, and you'll see the results of your efforts very quickly.