For anxiety: xanax (small dose) and beta-blocker half an hour before presenting. Also, knowing every sentence you're going to say by heart (it might require 5-10 repetitions of the whole presentation during preparation). With such preparation, it's hard to fail.
As you gradually get better at it, you might skip the drugs and do less preparation. The thing is, at least within a single job, the presentations revolve around a set of subjects and with time you will just master talking about these subjects. That's how managers do it - their jobs are pretty much mostly talking, so they get a ton of experience quickly and become very competent at presenting and discussing relevant subjects.