I've been taking a matte painting class for the past six weeks with Heather Abels through CG Masters Academy. Just two weeks left in the class, and I have learned so much!
We started the class with a project to turn an aerial photo into moving footage. Then we jumped right into working with footage for the rest of the course. I learned how to do some keying in Nuke for a sky replacement, building geometry from camera trackers, and creating a set extension from footage and simple geometry, I'm also learning more about good camera projection set ups, and how to sculpt the geometry for organic modeling so the elements don't look "cardy."
Here's a peek at my last project for the class. This is my initial geometry setup. I have a lot more sculpting to do, and need to break up some of the elements more. But this was a good start for checking the parallax and coverage for each of the elements.