Spend time writing about a topic as if explaining it to someone.
Then practice explaining it, speaking and drawing as if you were a teacher at the front of the class. You may figure out some other aspect wasn’t as clear as you thought and need to look into something.
Refine any gaps you reveal until you can share the topic fluently and clearly.
Then, simplify your language by replacing complex words and ideas with simpler ones and considering analogies to help people relate.