You will never improve your speech if you dont know what has to be fixed. First record a video of yourself making a speech, and starts to get use to idea. How are you going to be less shy to others if you cant stop being shy to yourself? After you realize that, improve your speech techniques like pitch variations, voice projection, tone, breathing techniques etc. And if possible, get a VR speech simulator to get used to the environments and adapt your brain to how to respond when a block occurs.