In the end it comes down to being able to communicate and listen well. Be an active listener and find out the problems that the C-level customer has. This could mean the actual business problem (sales needs to grow 10% and it hasnt for 3 years), logistical problems(my teams don't communicate), a political problem (I can't deploy a solution without getting the Network Solutions team invovled) - all are things 1) You should know about and 2) You may be able to fix.
That sounds simple, but it's really very hard to not get too wrapped up in what you and your company are focused on, rather than what this specific customer in front of you right now cares about. The best salespeople of ANY kind are very good at getting in synch with their customers - seeing the world, and their product from their customers POV and then seeing how their product fits into that worldview.
Some of the worst complaints I've heard is that the startup comes in all cocky thinking they have the best technology in the world, and doesn't actively listen.
I don't think I would be the best choice to give the talks. I'd be fine for drinks after.. I'm casually good with C Levels, but I'm a tech at heart, and having me explain things... I tend to do the bad thing of going too technical, and not realizing it before their eyes glaze over.