STEP 1: Know or research on what you want to speak on. This will give you natural confidence and even eagerness to deliver your speech
STEP 2: Never put in your mind that you want to impress anyone. This will make you nervous and too careful not to make mistake. As a result, as you talk, most of your concentration will be going towards that and so, you can’t think deep. Therefore, whenever you get stuck somewhere trying to recall something or you are asked a question, you will easily get confused and get into an infinite loop of dumbness.
Just have it in your mind that you want to say something!
STEP 3. Never fear or care about making mistake and people laugh at you. Tell me! Is there any one that learns something in a day and does it perfectly in that day without mistakes? The only way we learn is through mistakes because it is that way that we fill in holes of misunderstanding.
Any one you see great in something, he made several trials and let that who laugh at you continue to laugh while you continue filling in your holes. One day, he will cry for he will wake up and see that you have passed him already.
STEP 4: Read the history of Einstein and many other great minds, most of them started as below average in terms of intelligence but as they continue working hard filling in gaps, who is their match today? So why would you fear anything or feel that you are not gifted? The gift is in your hands; you make yourself what you want to be!