Manage trainee expectations by announcing at the beginning what will be covered in the training. You can do this interactively by asking them what they expect from the training, then match their expectations with what will be covered throughout the course of the training. Be straightforward early on in telling them what is outside the scope of the training.
Make sure while introducing yourself in the beginning of the training to highlight your experience and expertise in the field to create credibility for yourself early on.
A training session should be highly interactive and not a lecture. Top level trainers usually have a large repertoire of interactive tools and activities to maximize trainee learning and ensure sustained interest.
Interactive training methods include role plays as well as individual and group exercises. You can give participants assignments as groups, for example ask them to solve case studies as groups.
You can also make participants' introductions in the beginning a fun activity. One way is to divide them in pairs and ask them to find out some things about the other person, for example: their name, what they studied, why they are interested in the topic, what is their favorite thing to do, etc then each person introduces the other.