There are several types of delivery style for your presentation. by working out which one suits your natural performing style, you can play to your strength.
Trying to give a presentation using a delivery style that doesn't suit you can be painful, awkward and finally lead to an unsuccessful presentation. Choosing the right delivery style for you then, becomes one of the core components of presentation success.
The first style to consider is the IMPROMPTU speech. There is no advanced planning or practise. Since there is no preparation required, there's no stress and strain about creating the presentation's content. It's very free, you can riff. On the downside, it can be hard to stick to your point, you won't have easy examples, the speech will lack a planned shape and the level of impact is likely to be less affective. Without doubt, this one can also easily go wrong if you lose your thread or train of thought.
The next is the MEMORISED speech. This takes a lot of time in writing, it puts a lot of pressure on you to memorise and recall a speech, and if you have a lot of speeches to give, then you'll spend more time memorising speeches than presenting them. Don't get me wrong, they are impressive things MEMORISED speeches. But can you deliver the speech with the sense of spontaneity that a good speech needs - or it may just sound like you've done it a million times and that will seriously affect the impact on your listeners.
The third is the READ speech. Again, this takes a lot of time to write, but you won't have to memorise it. You will however spend a lot of time looking at your notes or the teleprompter - unless you train yourself to deal with this. The goal of a speech is to make a planned impact on the audience, it's hard to do this if they are looking at the top of your head for most of the speech.
Finally, we have the EXTEMPORANEOUS speech. Which is a mouthful by itself. It you don't want to just talk off the top of your head, and you don't want to read or memorise the speech. What's left? Well, it's the one that's considered best, the EXTEMPORANEOUS speech. The idea isn't to memorise a presentation, but to become familiar with the flow of the key ideas. These you practise speaking aloud, but you never need to decide on precisely what you're going to say. It's like the best of all the speeches, you get:
Structure without rigidity - you learn the structure, not the the words.
Confidence in your material - you can plan and structure
Choose key wording - without planning whole pages and paragraphs
Maintain spontaneity - you get the freedom of the impromptu speech
Learn the structure and shape, the key points and the transitions between sections and then speak with confidence and freedom.
You can choose any of the styles, but from my experience the EXTEMPORANEOUS speech will always give you the best of all styles mixed together.