One potential problem for some speakers is keeping track of where they are going in their presentation. One method is using notes. These notes provide a roadmap of where to go. Of course if you accidently shuffle your notes, you may put them out of order. If the font is small, they may be hard to read. Notes have advantages and dis-advantages.
Another simple method is to use a written outline. Then memorize this outline and turn it into a mind map. As you speak you can visualize this mind map to see where you are going in your speech. Of course, making the mind map overly complex defeats your original purpose. As you speak you can mentally see your major points and pretend there is a bouncing ball going from one point to another. Your minor points can be simply just words and your bouncing ball can go from one point to another as if you were watching subtitles on a movie screen.
The key is having a simple and effective method to lead your audience.