Attraction of attention (perception)
Do not immediately submit information, if your listeners are not prepared. Draw their attention. It can be:
-humor
-shock (Dr. House's reception)
demonstrative behavior
-increase in voice
All this will cause the curiosity of the audience and make them pay close attention to you.
Informing learners about goals (expectations)
You need to inform the trainees about the result they should achieve and what to learn, as well as what needs to be done with these skills and information. People not only need to understand what is achieved, but also why they need it at all. This is a very important step that will allow the audience to be more motivated. So spend enough time at this stage.