[amerkhalid]

I would recommend join Toastmasters.

Toastmasters has apparently helped a lot of people develop their public speaking skills. Their meetings also have impromptu questions, which help members develop fast thinking before responding.

I joined them recently. So far I am really enjoying their meetings.

EDIT: I see a few more people have recommended Toastmasters. I will expand a bit and say that Toastmasters should be first step. Reading books, meditation, working out etc are all good options but they help you with public speaking/shyness indirectly. But Toastmasters will help you with public speaking immediately.

It is free to attend their meetings as guest for as long as you like. You can try different clubs until you find one that you really enjoy.

After a while, you will get to know your club's members and it will get easy for you speak in front of them. But then you can join local competitions where several local Toastmaster clubs compete together. So you get to speak in front of larger and different audience and continue improving your public speaking skills.