An engaging presentation has a clear purpose; shows good understanding of the topic and its importance; is correctly pitched at the audience; and provides the audience with a key message to take forward.
Being a good presenter takes much practice. Practising and improving your presentations will also increase your oral communication skills and confidence.
Presentations are assessed on your content (what you present), your delivery (how you present it) and your visual aids (how they aid your presentation). Always check your assignment guidelines and marking rubric for specific information relating to your subject or discipline.