Amateurs practice until they get it right. Professionals practice until they cannot get it wrong. How you prepare will be directly reflected in how you perform. Personally, I find recording my talk and then listening to it very helpful. Simply take out your smart phone, put on your headphones, and record your talk as if you were in front of an audience. Then listen to yourself. As you do, you will find pockets of missing content and make tweaks before you perform in front of an audience.