1st of all, I need a written text of approximately 20 minutes in duration. I like my actual text to be shorter, to allow for some extemporaneous remarks. I never use powerpoint unless I am analyzing an actual painting or image. I never, ever put text I am going to read on a powerpoint slide. I'll use a handout if analyzing a poem.
Nobody ever complained my talk was too short
I won't improvise a talk, because I have points I want to make in a particular order, and certain quotes that have to be read into the record verbatim.
I don't write my text as I would an article. I write it in an oral style. As I read it, I often change the wording to make it even more oral. I don't care if I stumble a bit while doing this, or am not smooth at every moment. I never will be anyway, since I will stumble over a text read verbatim too.
Eye contact is key. Reading a text off the page almost guarantees that you won't be connecting with your audience. So I either know my text so well I don't have to be looking at it at all times, or I use enough extemporaneous remarks so that my nose is not in the text. The audience won't mind if you are reading (since that is standard procedure) as long as you still make an actual connection to the listeners.
I'll often move between verbatim reading and paraphrase. I'll find a better way to say what's on the page. But if I feel myself floundering, the page is a good anchor.
It is very easy to disengage from a speaker who is not looking at the audience. Because the speaker will never notice, so it's barely even rude to stop listening. By the same token it's hard not to pay attention to a speaker who is looking at you and talking to you.
Extemporaneous or improvised remarks can be planned. The important thing is that they don't seem to be read straight off the page.
When I read a quote from someone else, that is a dramatic reading. I milk it a lot. I also use voice and intonation to make my point during the entire talk.
I am not perfect or smooth, but I think I am more interesting to listen to than 90% of presenters. This is a combination of having ideas and having an effective delivery. I could work twice as hard as that and be in the 99th percentile, but I don't need to do that.
It's a little like writing. If you take pride in your writing, or speaking, you will already be better than almost everyone else. The average is pretty low.
It's bullshit to say that some people aren't "auditory learners" and hence can't pay attention to a talk with no visuals. Nobody likes a boring lecture by a disengaged speaker. And by the same token even somebody who doesn't normally like lectures will be engaged by an engaging speaker.
I am a bad listener because I know I can do it better than the guy standing up there. I want them to be listening to me and not to that guy.