Think about this peculiar fact for a minute: Your audience will forget your content, but not how you made them feel. Now take a minute and ponder on the balance of information content, expressions of affection and motivation in your lectures.
Years ago I heard a lecture by a professional genealogist known for his knowledge of Irish research. Unfortunately, there was no Irish wit, no charm no blarney and no magic connection with the audience. He had an underutilized Terry Thomas smille that could have been used charmingly but was rarely seen. But he knows his stuff! I could have been a motivated deciple.
I compare that experience with my experience listening to John P. Colletta speak on using newspapers to flesh out family history. John was witty, charming. and immensely informative with anectdotes to illustrate key points, and a heavy information load made light by his natural affection for his audience.
Thinking about the differences I am reminded of my sage advice to my son on finding a wife, “The hardest part of courtship is making friends. Once she’s your friend, conversion is easy”.
How do you make friends with 20-50 people from the front of the room?
Genealogy Education 
You said: “How do you make friends with 20-50 people from the front of the room?”
Anecdotes.
I recently gave a talk to my local genealogical society — it’s a good training ground for a beginner like me. The topic was “Our Black Sheep Ancestors: How to Approach Them.” I had mentioned to a friend of mine that I was going to give this talk, and she gave me a wonderful anecdote about one of her collateral ancestors from the Appalachian Mountains. It fit the topic perfectly, and the audience loved the story.
Jokes are also good, if they’re on point. But we do have to be aware that today we sit on the razor’s edge of ‘political correctness’ when we use them. Good taste and thoughtfulness are always good watchwords.