There are 4 possible ways to deliver your speech in public speaking. Each way has its' pros and cons. The method that s picked will depend on your circumstances. However, there is one way that is the most effective in the majority of cases.
The 4 ways to deliver your speech are:
1. Read it to the audience
In this way the speech is written out and read aloud word for word to the audience. When giving your first speeches this method is attractive because the speaker does not rely on their memory due to the security of the speech. This does ensure that nothing is forgotten and the speech is accurate. The disadvantage is that you lose your personal appeal because your head is bowed reading. And it is difficult to talk expressively and maintain a conversational aspect to your delivery. However it is useful in political and highly controversial speeches to read aloud to prevent misquotes or being sued.
2. Memorize and deliver to your audience
The advantage of this method is that you can employ phrases that you would not normally use and you are not tied down to reading your speech. You can look at your audience and move around. The difficulty with this approach is if you forget your "lines" and then struggle to determine where you are up to. Also the natural conversational quality of your delivery is difficult to maintain and it is often stiff and stilted.
3. Impromptu Speech
In an impromptu speech the speaker has not prepared a speech and is delivering his thoughts and word on the spur of the moment. This method is very flexible but rarely achieves the quality of a well prepared speech. It is best avoided if you can. But if you think you may be called on to say a few words it is handy to have a few "lines" prepared to avoid any embarrassments. Most experienced speakers have developed some reliable responses to use when they are called upon to make impromptu remarks.
4. Prepare a speaking outline and memorize the ideas
This approach is known as the extemporaneous method. The speech can be delivered with or without notes. When thoroughly prepared (which can include writing your speech in full initially) and practiced there is little need for notes. This is the easiest way for the speaker to achieve the ability to speak in a natural conversational manner. It also gives the ability to adapt the speech for any unexpected events. It does take more time and preparation than the other ways outlined here.
When starting out, it is tempting to read your speech or memorize and recite it word for word. Be careful with these methods because it is difficult to connect with the audience.
When called on for impromptu remarks ensure you have a few memorized responses (an emergency kit). The preferred method is to prepare thoroughly for your speech and memorize the ideas. Your speech has the potential to be more natural and to be more effective in achieving your purpose.