For me taking a breath of air before the word I'm gonna stutter on, and then using that air to help the word flow out. Also light articulation, just being really soft with my mouth/lips and being lighter on the first sound and then more normal on the rest of the sounds. Sometimes I kinda skip the first sound all together and people dont even notice. Like I'll say something like "ank you" instead of "thank you." Also prolongations help me a lot. So instead of sounding like n-n-n-n-n-n-n-n-athan it'll be more like nnnnnaaaathan. For me it's less stress on my face and feels like it flows better.