1. First of all get rid of your fear. You are unique and so are your skills. Most of the time people fear speaking in front of people and on stage. So try not to think of it and take it lightly and focus on your strengths.
2. Practice a lot. Practice in front of Mirror. If you are giving a presentation, revise and rehearse in front of mirror. Ask your friends and relatives to listen to you and give feedback. Improvise on it.
3. If you are going to face an interview, try to make a note of all possible questions, do some research, and create some sample answers. Do not learn them, just keep points handy on which you can talk comfortably and easily.
4. Ask your friends to take mock interviews.
5. Read a lot. Read newspapers, books, magazines. Find tough and new words, keep a dictionary handy and note down word and meaning. Revise in next few days.
6. You can practice english vocabulary on http://www.complore.com/word-power-made-easy