It mostly taught me to NOT use a publishing company. I was so excited when a company reached out to help me publish my first novel. They super conned me out of a lot of money and time. The only thing I got out of it was my cover, but even now I'm debating on a redesign for that cover. It also taught me to really enjoy the writing process and to not rush. There is a lot that comes with publishing, and if you rush it, your story won't be as good.
I've been writing since I was little. I even still have the first books I ever "published" at my school from 2nd, 3rd and 4th grade! Mostly I have a lot of stories in my head, and I just try to get the good ones out on paper before I forget them, or a new idea comes and kicks out the previous one.