I still struggle to get everything in the right spot on the page. I thought maybe I could help myself get over this hurdle a bit quicker if I practiced viewing objects through picture frame glass marked with a grid, and drawing on a Photoshop file or piece of paper containing the same grid. I think it works pretty well.
I thought this might be considered a crutch, but it’s actually recommended in a lot of art books as a way to train yourself to measure. Eventually, you’ll be able to gauge all this stuff in your mind.