7 years of practice helped me. I started doing it as an actual hobby in 1999. I was 8 years old. Yeah, I look back at my pictures now and I'm suprised I didn't give up because my stuff looked so crappy. I didn't think I was a bad artist back then. I really, really can't see why I didn't. I didn't think I was SUPER good either. I thought I was average. I used to just draw my own stuff without copying and then in like 2000 I did both. I copied sometimes for reference. (never traced though, I'd feel too guilty if I did and said it was mine)
I just copied sometimes because it made me better and I thought it was kind of fun. My copied stuff looks better than my drawn stuff from back then of course lol.
Now, I don't copy whole pictures anymore. Except, I copied one picture for a Fan Art contest in, I think July, on re-creating your favorite comic/movie moment. I made some changes to the pic though. I told everyone I copied it and just changed some stuff.
But now, my other art is all by me. Sometimes maybe I have to look at something for one part of it maybe. Like a hand that's too hard to draw, look at action figures for ideas on poses and character angles, etc. Action figures are a bad reference sometimes. You know, their body parts aren't perfectly real, if you hold YOUR arm up your shoulder goes up too, but action figure's shoulders don't move.
So I rarely do action figures. Another way is look at your own body parts for reference. Stuff like hands, feet, arms, poses, etc.
I think I learned mainly from reading so many comics growing up and seeing the art. Then the style and ways it's drawn got burned into my head. I read comics today and go "Oh, that's how lighting is done when you're in front of the sun" "Oh that's how you draw this guys head from that angle"
It just goes on. I also do manips in PhotoShop. I started that in summer 2005. I color my art in PhotoShop too.
Just practice. I'm 100% sure that practice makes perfect in this area.
I hope I helped.