What's common between singing and presenting

This weekend our son will be singing a solo in church. Yesterday the lady who is the best soloist at church gave him some advice in getting prepared for his upcoming solo. She told him to make sure he knows his music and the words so that he can concentrate on the performance and not worry about the words or the notes. Her advice is the same I give speakers. Know your message so well that your presentation then can be a conversation between you and the audience. How do you get to know your material so well? It doesn't come from creating your presentation on the way to the meeting, that's for sure. It starts with a clear goal, a structure that moves the audience from where they are to that stated goal, and visuals (PowerPoint or others) that support your points. Then you need to both practice and rehearse. Practicing is running the presentation through in your mind, making sure the pieces fit in the right order. Rehearsing is standing and delivering the presentation, where you are checking for how the words sound, timing and fit of visuals with the words being spoken. If you do these things, you will know your message and your presentations will be more relaxing and more successful.