To do this take yourself out of the equation, yes you are singing/performing but its about the song not us... If we can separate ourselves from this process and focus fully on the song and the interpretation it will automatically come through you... You are the instrument...
Forget about hitting the right note, we may or may not make mistakes and that is ok. The Perfect Performance isn't about singing perfectly... We can do that, and it be a boring performance - think about it! What we want to focus on is how we will interpret the song and getting into that zone so we can fully express it.
No one will say didn't such and such look silly expressing that song...
What they will say is WOW! that was awesome I really felt what you were singing about... or
WOW, I can't believe you did that, I couldn't do that... You were so confident!
Capture your audiences attention, bring them into your story... You will find that once you master this you won't want to stop!
If anyone else has any tips and tricks please comment, what has been successful for you? What do you love about performing? How do you combat your nerves and connect with your audience?