One major weak area for a speaker happens before they say their first word. The transition from when the Master of Ceremonies (MC) leaves the platform and the speaker begins to speak can be confusing for the audience. Some people are watching the MC sit down. Other members of the audience are watching the speaker come to the stage. Maybe the remaining audience members are just surfing the web on their phone because they assume nothing of importance is going to be discussed. This transition period can be either a great prelude to a speech or the waste of an opportunity. This is why introductions are so important. Every introduction should be personally written by the speaker. Do not leave this duty to the MC. Always make 2 copies with a large font size. Before the event go over your introduction with the MC and ask if there are any questions. Always keep one copy of your introduction for yourself, in case the other is lost or misplaced by the MC. As to the length and detail of your introduction that is a personal matter. My thoughts are the audience has come to hear you and not a book length version of an introduction. On the other hand, your introduction is a little bit of you so that your audience gets a hint of the essence of you and what you will speak on. With practice you will gain a feeling of the perfect length for your introduction. After the MC has read your introduction and passed the stage over to you, you wait for the MC to sit down. Then before you start to speak, mentally count to five, as you slowly gaze at the audience. This will allow the parts of the audience who are not quite paying attention to refocus on you the speaker.