Rehearse in chunks of material. Chunks are usually Introduction, Main Point 1, Main Point 2, Main Point 3 and Closing. Rehearse a chunk at a time for several times. This will make it much easier to learn than trying to rehearse the whole talk at once. Connect to your listeners.
Connection is the essential element to an impactful talk.
Connection is a two way exchange of attention. It is a giving and receiving of universal human energy. It is much more than eye contact. To connect you must see and speak to your audience members as individuals. And you must let them see you as a person.