I feel like every stutterer it a bit different. Growing up I was one of the ssssss, th th th th repeating types. Over time I have become a speech block stutterer. To me one of the worst things is the fear. It's like a self fulfilling prophecy. What helps me is to take notice of the letters that cause me to block and practice them. For instance with B words, I find that push my lips together way too hard and build up a lot of pressure in the my throat when I am having a block. So I will work on pressing the lips a bit more gentle and not allow all that pressure to build up.