What helped me a lot was learning design specifically. Not in a structured fashion, but I picked up bits and pieces about grid systems, vertical rhythm, color theory, typography, etc. While I was doing that, I also learned from the descriptions what an art person would look at. What's their way of thinking? How do they look at content as shapes on a drawing board? How do they guide attention?

The result? I'm "ok". Apart from the current website I made with my wife, I mostly made relatively simple designs which I could at least look at. Theory really helps provide guardrails, rules to follow. Later you can stop following the rules once you know what you are doing.

Edit: I also find multiples very helpful. For a website, I'd start with a base line height of 1.5rem and make everything a multiple or divided by a whole. Menu height? 3rem. Border radius? 0.75rem. Padding? ... You get the idea. Later on you can bring in stuff like golden ratios. When I started 3D stuff, I did the same in Blender. I moved everything via the coordinate box.