Know you're talking about. That alone will make the talk more natural, as you'll be able to adapt to your audience due to having knowledge outside of just your research.
This was the biggest change between the presentations I had to give in high school and the ones in college and above. In high school, the topic was usually given to us, whereas in college and later, I got to choose the topic I was most knowledgeable about. The latter meant I was more passionate, more able to answer audience questions and more able to tailor the delivery to the audience.
One piece of advice I heard was that if you absolutely have to talk about a topic you're not familiar with, talk about being a beginner in that topic. Talk about your perspective as an outsider learning that topic in the first place.
To expand on that with "obvious" advice: Know your audience. Present accordingly.
Are you an expert or a beginner relative to your audience? If I'm explaining something technical, I might take a more assertive tone when glossing over details with a novice but speak with more deference to an expert. (e.g. Throw in a few "I think ..." or "My understanding was that ...")
Getting a quick grasp of where the speaker is coming from helps the listener really engage at the right level. Should I double check what the speaker is saying or are they the authority on the matter? Nothing get's eyes rolling faster than someone making blatantly wrong factual errors overconfidently.
+1 I gave a lot of conference tech and HR talks and always failed when talking about something I didn't have deep knowledge about, but thought "that would be cool, now read about it"
This was the biggest change between the presentations I had to give in high school and the ones in college and above. In high school, the topic was usually given to us, whereas in college and later, I got to choose the topic I was most knowledgeable about. The latter meant I was more passionate, more able to answer audience questions and more able to tailor the delivery to the audience.
One piece of advice I heard was that if you absolutely have to talk about a topic you're not familiar with, talk about being a beginner in that topic. Talk about your perspective as an outsider learning that topic in the first place.