It's got nothing to do with you.
That's right! It's got nothing to do you with you. I know, YOU are up there, it's YOU that everyone is looking to, YOU have worked hard on this speech, pitch or presentaion. Here's the thing: the audience is more interested in what you are about to teach them and the information that you have to share, than they are in YOU. It's your information- not you the person.
We get hung up on me, me, me: am I doing it right? Do I look dumb? Did I walk where I was supposed to walk and say what I was supposed to say? As soon as you take the focus off of YOU and put the focus on the AUDIENCE and the INFORMATION- you're home free. Coaching comes in handy to get the information across in a dynamic, entertaining way.
Ask yourself 'what is this about'? 'What am I here to do'? Usually it's because you need to:
Win over an account. In this case- focus on getting yourideaacross, teachingyour idea to others so they will want to use it (and hire you).
Give a speech about what you do and how you got where you are. In this case -it seems all about you, but I would ask you to fucus on your process, enlighten your audience, take them on your journey. You want them to understand how you got where you are. That becomes about them learning and not about you.
Give a presentation on your work. In this case- focus on the work. Ask yourself 'how can I explain this work in the most intersting yet clear way'. That will allow you to think about the 'how' and not the 'who-(YOU)'.
Once you figure out what your wearing- which dress, which suit and tie or which pair of jeans, then forget about 'you' and focus on the 'doing'. You'll be much more comfortable up there and you'll conncect with your audience! That's the goal.