Delivering a presentation in front of a live audience demands a great deal of self-confidence that allows the orator to overcome his fears of failing. In public speaking, and in life if you do not perform a task perfectly, you might face a minor setback but you are able to accomplish the overall goal, as long as you try.
Sometimes the fear of failing can have bigger repercussions than actually failing.
While delivering a presentation, you might make small mistakes that you can instantly correct in the next moment or you might forget to mention an important point in the right sequence but that should not discourage you from trying. If you make a mistake, learn from the experience and make your next presentation better.
Check out this infographic from Malcolm Andrews; an ideal resource for any budding public speaker who is interested in refining their presentation skills.