Be involved in the community, help new users, update often (but not under the 24h mark then your story won't show in the Fresh section where new updates and stories go). Have a good cover and summary, if you're a writer, stick to around 600-1k words but it can work to have longer chapters as well. Schedule chapters ahead of time so readers know when to expect a new chapter.
Use your author's note to promote other creators or show a glimpse into your personal life. Respond to commenters, they will appreciate it.