What’s the most important thing when giving a pitch?

I’ve been wondering what’s the most important thing when preparing a pitch or presentation for your customer or investors? I tend overprepare (not a bad thing defiantly..), trying to cover everything, but I rarely have enough time to go through it all. Then there’s the nerves, balancing a good story, clear delivery, and a polished deck feels overwhelming.... so how do you prioritize when preparing for a pitch? and do you think the pitch deck is important? I always struggle between making it visually impressive and keep it simple... Would love to hear your thoughts!