Communication issues

I think speaking in public is a really difficult job because everybody is looking at you so, every time before I have to speak in a presentation I get very nervous like many people in the world, but right away I start speaking I feel more comfortable. I like to see different faces while I am speaking; however, it is sometimes tricky because I lose my concentration on what I am doing. I need to work on my presentation several days before to expose it; otherwise I don't feel secure at the right moment. When I am in the opposite side and I just have to listen and looking at people who is speaking I think I always observe more than listen to them because the first impression come from my eyes. In spite of observing is more entertaining to me I like listening as well.