Get good at draftsmanship and backgrounds. Learn to shade properly. Have solid anatomy and gesture. Be willing to put in a ton of time coming up with and putting in all the tiny details. Learn how to do proper line art. Learn color theory. Learn whatever software you're going to use to make the art. Learn how fabric moves and folds. Learn how to render complicated textures onto surfaces in your work.

Then, use a digital paper filter for that fine, on paper look.

You start with putting pencil on paper. This artist SimzArt actually inspired me to try learning art a few years ago, but i didnt really start to put any effort into it until just this past year. Its a skill like any other that can be learned it just takes time and dedication.

Before i started to really dedicate time to study and practice, my "art" was so bad. I basically started at level 0 i could barely even draw a convincing stick man.