It's difficult!
For me, I found that learning to analyse or critique other people's work helped a lot. I was really overconfident when I started making comics, because I was a small-town artistic prodigy as a kid, always being told how exceptional I was. I thought I was practically pro standard and that all the polish stuff that made book art look different from mine was just like..."IDK they just put it into the printer and that stuff just happens".
When I started spending time around more experienced aspiring comics creators online, I came down to earth with a bump. "Oh, you need to make your gutters more consistent", "Hey, your shot distance and angles could do with being more varied", "Hm, maybe look up some comics fonts and read this tutorial on speech bubbles", "Here's a good book on anatomy" etc. I realised that other people didn't just get given that polish, they created it by themselves through pure effort.
I started to study comics I liked on more than just a surface level, and the closer I looked, the more I realised how far I needed to climb. Yeah, my anatomy was good for a teenager, and wasn't bad when characters were in fairly neutral poses and viewed from a straight-on angle, but my skills simply weren't good enough to draw to that level while changing the angle up, I was limited in body types I could draw, and on poses. So I started to study really hard.
The devil is in the details. When looking at other people's comics, look at things like their colour palette choices, their line quality, their design elements like fonts and speech bubbles, their visual storytelling, or things like the proportions or sense of mass on characters. When you find somebody who really excels at something, try to think about what you can learn from it. Every creator has strengths and weaknesses, so look for what they do well compared to what you do well. It's not unusual to be better at a creator around your level in some aspects, but for them to be better than you at others.
And if you're still struggling, you can always ask for reviews! 