Develop public speaking confidence without the audience

You will read about, or have heard about, strategies to overcome public speaking nerves. In preparation for implementing those strategies in front of an audience, you can try them out in ordinary, non-threatening situations first.
For example, take note of how you conduct a conversation – with strangers in particular, for example a shop keeper, bus conductor, or a person to whom you are introduced at a party or function. The communication and confidence strategies you find yourself using naturally can be used in your public speaking.
And, conversely, if you want to improve the communication skills and the confidence, try practicing some of the strategies you have been gathering for public speaking, in those conversations.