A recent study showed that singing and humming helped those with stuttering problems. Hope this helps.
I know this is clichéd, but deep breaths work a charm (not that I've ever had a crush whom wasn't a friend. Nor have I ever had a serious crush on someone).
-TFP
The Stuttering Foundation of America, states that “overcoming stuttering is often more a matter of losing fear of stuttering than a matter of trying harder.” Stuttering should not be a taboo subject. A friendly smile and an occasional kind acknowledgment of the problem can put you more at ease. Perhaps you could say something like this: “Sometimes it is not easy to say what I want to say.”
If you begin to stutter while speaking, then, as much as possible, keep your voice and manner calm. Relax the muscles of your jaw. Use short sentences. Minimize the use of interjections, such as ‘um’ and ‘ah.’”