Every Saturday I take my son to his music teacher, the different ways of practice that his teacher teaches him is equally applicable to public speaking. Whenever he made a mistake, she got him to start from a few notes before the mistake and carry on a few notes after the mistake, rather than going back to the start each time. This meant that the part of song that needed the most practice got it, rather than becoming excellent at the first part of the piece and then gradually getting worse as it went on. She also made him practice in various styles and speed. This kept him interested and also started making him versatile.
It is good idea to aim to memorise your speech and have notes or cue cards to refer when needed. But as you get confident you should aim to become less reliant on your notes and to leave the script behind at times and just go with the flow. You may find yourself with a different audience to what you prepared for and they may appreciate a different angle on your material. Being able to adapt and leave your script behind so that you can present your material in a way that is more meaningful to your audience is a great skill to develop.
My mentor at City of PerthToastmasters usually speaks without any notes. She prefers to have a feel of the audience before the speech and then covers the things that seem most appropriate for them. I have seen her deliver a speech drastically cutting out points that she had prepared, because it didn’t appeal to the audience. She happens to be an extremely inspiring speaker, but the ability to do this didn’t happen overnight, it is the result of many years of experience.
Once you are happy with your speech manuscript practice stage rehearsals. By this I means shut yourself in a room and actually perform your speech as you would to an audience, even get someone to be your audience if possible. Say the speech out loud rather than just mouthing the words. You may find that something that looked good written down doesn’t sound so great when you say it out loud. Remember to practice the body movements you have thought off.
As well as the actual words you’ll say you should also rehearse the technical side of your speech. For example, are you going to use a wireless microphone so that you are free to roam around? Or is the microphone fixed to a lectern which means you’ll have to stay behind it to be heard? Are you using the projector? When does the slide change? Is your speech speed in sync with the slides?
If you’re going to take questions at the end of your presentation then give some thought to what sort of questions you might get so you’re not caught off guard.