Never ever apologize for your speaking abilities. Even if you have only the speaking ability of a terrified mouse, you'll just increase your suffering.

Apologies can take many forms

An apology can be verbal: 'Sorry, I'm not a public speaker. I'll keep it as short as possible.' Or it can be simply an expression on your face that conveys a similar feeling. You might argue that it's okay because you're just building rapport. You're being honest and humble - which, surely, are virtues. Aren't they?

What audiences think

No. Audiences hate it. They groan internally, partly because the I'm-no-good apology is ingratiating, partly because it conveys fear and submission. It says:

I want to lower your expectations to that you'll judge me by an easier standard.
I don't want you to feel let down at the end, so I'm doing it now.
I don't want you to think that I think that I'm good at this.
Please like me.

It's also self-fulfilling. It paints you into an even tighter corner, constraining the abilities you do have.

This witticism from Kin Hubbard: "Why don't the feller who says, 'I'm not a speech maker' let it go at that instead o' givin' a demonstration."

Well, that's cynical humour. So let's change it to this.

Have the courage to speak without apology

If you're nervous, make yourself speak anyway - with no reference to your lack of ability. If you're nervous, the audience will see it and credit you for your courage in the face of fear.

Michael