The main character usually changes in some way over the course of the story, but that change must feel organic and natural. You can set up a big change of mind with foreshadowing and having them change on some smaller matter, showing that such change is possible, so it doesn’t throw the reader out of the story when it occurs.
We discussed approaches to learning more about your characters. I recommended the book Writing The Other by Nisi Shawl and Cynthia Ward, which talks about writing characters who are a different sex, race, or class background than yourself. I also recommended people-watching and reading pop psychology (or even more sciencey stuff, which will provide all sorts of story ideas.
One of the quickest ways to turn an editor off is with improperly punctuated dialogue, so learn the rules and use them. We went over things like speech tags, how to punctuate internal dialogue, why you don’t need to come up with a bunch of synonyms for “said,” and how to make voices distinctive. I suggested that people watch the wonderful adaptation of Terry Bisson’s “They’re Made Out of Meat” – here is the original text, and here is the film made from it.
If you really want to focus on dialogue, read good plays, which are pure dialogue. If you want to write in a particular historical voice, one of the best ways is to read deeply in that period so you absorb it. Doing so may make you aware how much what we read and watch creeps into our writing – that’s one very good reason to read some high quality stuff now and again.
Enjoy this writing advice and want more like it? Check out the classes Cat gives via the Rambo Academy for Wayward Writers, which offers both on-demand and live online writing classes for fantasy and science fiction writers from Cat and other authors, including Ann Leckie, Seanan McGuire, Fran Wilde and other talents! All classes include three free slots.
Prefer to opt for weekly interaction, advice, opportunities to ask questions, and access to the Chez Rambo Discord community and critique group? Check out Cat’s Patreon. Or sample her writing here.
Writers get told they must blog, but not a lot of advice about it. I’ve talked about this more than once, most notably in 
One Response
I’d like to recommend a blog that has helped me get into my characters’ minds: http://blog.liviablackburne.com/
Livia is a brain scientist and a writer, and she has some excellent posts on psychology topics related to writing. I especially liked a post she did on her husband, discussing how male friends relate to each other: http://blog.liviablackburne.com/2011/02/on-writing-realistic-male-characters.html