The best thing I did as an adult was go to Hollins Communication Research Institute. They run a 12 day intensive treatment course that focuses on retraining your muscles to function like a fluent speaker, because stuttering distorts the position of the jaw and tongue when making sounds and also messes with how you breathe. It’s not cheap, but it helped me more than anything and even almost 10 years later, I can still call up the clinicians to ask for help or just to check in. Standard speech therapy can be helpful for some. It wasn’t for me personally. But then again I was in therapy for years in grade school with therapists who weren’t trained in stuttering and actually made my stutter worse, so there’s that.