Don’t prejudge what you think is good or bad when you get to the point of submitting your work...You may have to start small at first, but as the Bible says in Zechariah 4:10a – “For who has despised the day of small things?”
I’d say the biggest assist in writing well is reading. As much as you can. I do it for the fun of it, or for information, or for spiritual development. After a while, you develop a sense of what reads well and what doesn’t.