Oh man, I learned this the hard way last year when I did a full cape for a cosplay. I spent like three hours getting the neckline and collar area perfect, then realized the cape sat right over all of it and you couldn't see a thing. What worked for me was prepping the neckline but keeping it simple, just enough structure so it didn't look sloppy from the front or side, then putting my real effort into the parts that actually show, like the shoulders and where the cape attaches. The trick is making sure the neckline still looks clean if the cape shifts or someone peeks under it, but you don't need to go all out on detail work nobody will ever see. I also started pinning the cape in place early so I could see exactly what got covered before I wasted time on it. Saved me a ton of stress and honestly the whole thing looked better because I wasn't rushing the visible parts at the end.