They say you should rehearse an hour for every minute of your speech. I’m not so sure.
I think rehearsing your talk is really important. But how you do it, probably differs by individual.
There’s a belief out there about saying it in front of a mirror. What’s THAT about? Forget it – it doesn’t work.
What I do is break down longer talks into chunks – subtopics or key points. I get the main point in my mind and then I write down a word or two on a cue card. I memorize or think through the logic of the argument I’m going to make so that a key word will trigger that chunk.