I have found that there is an art to delivering. Having confidence in what you say, having control of your classroom, and being honest are all part of being able to deliver effectively. Don't be too starchy but at the same time never take yourself out of your professional environment. I am not saying you can’t have fun in the classroom. I believe the students are watching and in many cases, there is one or two that are waiting for you to make that mistake or contradiction or just a little inconsistence so they can call you out.