Deep diaphragm breathing is key. It was called the Full Breath Target in my speech therapy course. Absolutely essential, but I don’t know how you can incorporate that into a practice without formal instruction. Not as well, at least. I haven’t read the book yet, but the guy who developed the program I went to is Ronald L. Webster. He wrote a book titled, “From Stuttering to Fluent Speech…” it might provide some useful tips on how to approach your speech difficulties until you can afford some structured speech therapy. It’s on Amazon for $23. But have no illusions, you will always have to manage it. It won’t just go away like a bad cold.