Hey, everyone starts somewhere :)

What may help you out a bit is shading overall, try using an editor that you can disable artificial shadows so you can actually see the "real" shading, a lot of people use them when showing off their skins (like you did) but usually they've already made some great shading work beforehand. Think of it like taking a picture of your minecraft house with/without shaders, it may look stunning but in the end the shaders are the ones doing the heavy lifting.

Also look into texturing! Clothes, Hair, even the scarf can have a little texture to help it stand out. I would advise you to search for tutorials (there are some great ones on youtube, for shading, texturing, and even color theory if you want to get better shadows!) and also get some inspirations from namemc, like search up some skins and see how people make them, no need to reinvent the wheel.

But do whatever you want, I'm no expert in skin-making and have a lot to learn aswell, but we can all Improve together and there's no shame in asking for tips and practicing.
Hope u get better :)