@Sophie-Lawson Oh yeah, ellipses! They are so difficult to get right, kudos for trying to tackle this difficult and super useful tool!
@Kevin-Longueil I'll have to check out Framed Perspective! I have Framed Ink and I love how it's pretty simple, and yet how I keep learning more from that book each time I revisit it.
Another amazing book is Scott Robertson's "How to Draw". It's my bible for this kind of constructive approach to drawing objects and environments. It's such a simple title, and in fact I didn't pick it up for so long because I thought it sounded too basic, but it's the one I reference more than any other. So incredibly packed with great information on how to draw objects that feel like they're sitting in a real space.