So I think the first step to overcome stutter is to optimize your personalities..at least don't panic before speech and don't be sensitive and perfectism in speech and finally get more frustrated as the ending.That's a vicious circle. Can't say every introvert will get stutter but I think there are more possibilities for them to get stutters than outgoing ppl.And it's the same with sensitive,perfectionism ppl. I also think OCD will deteriorate stutter.Anyway stutter is highly relevant to one's personalities and mindset.And if u got some mental disorders,stutter will be deteriorated.