This ^^ if you want to still have mainly natural dialogue but want to get across main points or certain things that you want to say, just make a bullet point list and run through it a couple of times before you start. Keep it near you in case there's anything you forget to mention. Also, I think the main thing is just
practice! It may sound cliche, but it really is the way to become more natural and relaxed on the mic. Don't expect yourself to be great straight away - no one is great straight away. It takes a ton of practice and getting used to talking through this medium. The more you practice, the more relaxed and natural you will be and the more confident you will be. Don't worry about saying "uhmmm" or "and", these are natural to say too, as long as your content is entertaining/interesting then those things won't matter at all. I hope that helps
