Giving your talk a clear structure will not only make it much easier for the audience to follow and to remember, it will make it much easier for you to deliver.
I worked with a client recently who had prepared for his session by writing out everything he could think of to say, in the form of a script. When he came to deliver it, he found himself constantly referring back to his notes and looking down at the worst moments, such as when speaking the name of his company.
This is a very common phenomenon and it’s easily solved. First of all, as I’ve said many times, dispense with the script and go with bullet points. If you have a full script in your hand, it’s practically impossible not to keep looking at it and you end up reading.
The other big lesson, though, is to invest some time in planning the structure of what you want to say. If you’re delivering points randomly, of course you have to keep checking what’s next. If you have a clear shape and direction to your talk, if it flows logically, you’ll get into that flow and be able to speak naturally.