Whoa that is a question I am not sure how to answer. Basically, I break it down into steps.
1. And frankly, the most important one you could do, keep writing and improving. Writing is an art, and you can never be perfect. Write for yourself first and foremost. Write the story YOU want to write.
2. And this one can get difficult sometimes, but will teach you a lot of skills! Reading other people's work, and maybe they'll read for you! I know some people do Read for Reads, (which personally I find a hit or miss) or book clubs! Book clubs are definitely a help for improving your work and getting more eyes on it.
3, which can also go into 1: Do not give up, even if you want to. You just have to keep at it, and you'll get there.
I'm arguably not as successful as some wattpad writers on here, so take my advice with a grain of salt! However, those are the main three that's usually universal with everyone!