Lines and ellipses are great in general. They do get a big of wobble at times, so let me remind you that you should always prioritize confidence over accuracy always just in case.

I recommend drawing through ellipses only 2 times, as you've been drawing through them more. To keep it cleaner.

Boxes are pretty neat in general as well. You do get some wobbly lines here, so remember the same, always confidence > accuracy, even if they accuracy falls off, focus on confidence. And perspective have issues on the organic perspective, but p good overall like I said. Perspective is something you'll work on on the box challenge, so don't worry too much.

You can also add lineweight to the parts of the silhouette of boxes that overlap with others. It clarifies their relationship in 3d space a lot, so I recommend doing it.