One of the first things you should do is record yourself speaking. Play it back and see where you need more work- if you paused, ramble, etc. Refine and repeat.
Next, speak in front of a supportive audience like your family or friends. Sure your loved ones will sugarcoat it and tell you you were better than you were, lol, but this helps you gain confidence speaking before people.
Then, start out with a small audience. Grow the audience as your confidence grows :)