A trick that isn’t a solve all but has helped me is where you press your tongue to the top of your mouth silently just before saying a word, the tongue press acts like a first syllable to a word, which is where you normally stutter. If you stutter on the tongue press before your about to say an actual word, nobody knows because nobody can see that your repeatedly touching the roof of your mouth with your tongue. Not a perfect solve all but it has worked pretty well for me for a good number of years.