Communicate like a real person. If they like you, you’ll be more persuasive.
Being more likeable in writing
Write in a pleasant, informal way and your readers will be more likely to accept your recommendation or proposal.
Write like a bureaucrat and they’ll probably just skim through it and ignore your argument. The writing will be boring and they’ll dismiss you as well.
Being more likeable as a speaker
It’s the same when you are on a platform. Speak in informal (but usually not casual) language.
Don’t talk to the masses, but as if in a conversation with one person. You might say:
You might be worried that it will cost too much
Here's a less personal way of saying the same thing:
Some in the audience today might be worried that it will cost too much.
Connect with your audience
Lighten up. Build your relationship. It's usually more valuable than your PowerPoint slides.