The single best thing is to meet with the most constructively critical mentor you have who has also done it before. And do the pitch with her first.
Not someone that will listen to your pitch and provide a few supportive thoughts.
Someone that has been a successful founder AND knows enough about you to be direct. And tell you what needs to change in your pitch.
Expect to be interrupted. Expect the pitch to be ripped apart. Expect your intro in particular to be criticized as terrible, as rambling, as undifferentiated.
And then ask if you can come back in a week and do it again.