I used to think I was crap at drawing, until I realised real artists are allowed to rub things out. I still am crap at drawing, but now I make them better by rubbing bits of them out and trying again.
You do preliminary sketches, and refine the work over time, usually using a lightbox or similar. Or at least work lightly or in blue at first to get the basic forms down. Yes, erasers exist but also you get the foundations right first until you know you'll be putting the details in the right place.
My process even includes - often - scanning the roughs into the computer so I can work small at first then print them out and ink larger ... first perhaps altering the shape of them in Photoshop [Liquify, Warp, etc], making changes and thinking about what I'm doing before committing to a final ink.
People say that writing is rewriting, and that's never really been true for me. But for me, drawing is redrawing. My first sketches are always scribbles - a tangle of lines trying to figure out exactly where the lines should be going. Each subsequent draft tames those lines down further and offers more and more clarity. Often that's just placing a line in the exact middle of where the scribbles suggest it might go. Often I'll think I'm done with my pencil sketching, but decide to do one more pencil draft to really clean things up before I ink, so there's absolutely no question about where my ink lines need to be going.
It's absolutely not about getting it right the first time you put pen to paper. It's about planning and sketching so that when you do finally put pen to paper for the final, you know exactly where everything is going to go. Or, in a painting, getting the structure and proportions and forms right so everything's the right size and you know where it's supposed to be before you spent a lot of time on the detail.
I absolutely put a ton of time and thought into everything I do to refine it until it's "right." That includes cleaning up and redrawing some of the lines in Photoshop after the "final" inked art is scanned, since I can zoom in and catch any mistakes.