I'm shy, I talk really fast, like, at incomprehensible speeds, I avoid enunciating my words, and I make sure there are no emotions on my face as I'm talking. I don't like making eye contact, I always look down or away when I talk to people. More often than not I don't even listen to people, and I might agree to do something without really knowing what they just said. "Yes sure....... Wait what?". I have really bad body language too, my friends can't tell if I'm joking or wanting to be taken seriously. I also end conversations very quickly.
However, I still get by... somehow 🙂
Only time I'm a little confident with strangers is when I'm drunk, lol, but that's not really a suggestion. My suggestion is to try putting yourself in slightly uncomfortable positions, and then taking it from there. Maybe start with your friends and family.