Talking fast is probably the worst thing a stutter could do. The trick is to practice talking slowly. Like I told someone else recently. This is what helped me the most although I still sometimes slip up. As I talk, with every word I say, I make sure I move my lips in an exaggerating way. Kinda like I'm trying to perfect how I say every single word that comes out of my mouth. During certain words or during a lot of words, your two upper front teeth are hitting your bottom front teeth. I know this probably sounds weird but it works for me. I also don't know if it makes any sense to you or not.