I've been listening to the Comedian's Comedian podcast recently and I've chanced across the odd thing that might be relevant for those thinking about presentations.
For instance, 6 minutes into the Dara Ó Brian episode there's talk about how we always starts with a couple of 'Trust Me I'm A Comedian' jokes. Nothing complicated just guaranteed laughs before he gets into anything improvisatory or fancy. 'Trust Me I'm A Comedian' is a good way to look at it. Establish some trust. Establish you know what you're doing. That's why banging straight in with a story, or maybe even a fanfare, is useful - it shows that you've done this before.