Update frequency is basically number one on RRL. If you do that, you're pretty much 90% of the way there.
A few other things you could try:
- To get even more updates, if your chapters are long enough, you might consider actually breaking them up into smaller chunks. A lot of the stories on the top weekly fiction list have daily or twice-daily updates of only a couple hundred words. Of course, this is your personal decision, as where you end a chapter does affect how the reader experiences the story. I personally update once a month with a 3k word chapter, and I do well enough
- Participate in the forums and link to your story in the signature. The vast majority of RRL readers actually don't go on the forums and only read, but you will get a couple of readers this way
- There's actually a Promote Your Webfiction section in the forum where you can post your story synopsis. However, there is a "no bump" rule, so unless one of your fans goes there and starts discussing your story, it's very easy to get lost in the huge number of threads there
- Make sure your fiction is tagged properly so that someone using Advanced search can find it easily. Some people put every single possible tag, which I consider a bad idea, since then the reader has no idea what the story is about. Other than "mature" and "original", I'd say 3-6 tags is a good number
- Write author's notes and get your readers involved. Let them know explicitly that you enjoy getting comments and reviews. Encourage them to rate your story. While getting on the Top Weekly Fiction list is all well and good, the list with much more longevity is the Best Rated/ Active Top 50, which involves getting good ratings, and a lot of them.
- Participate in the writing contests. They don't happen that frequently (basically when the staff have enough time to read a bunch of crap and decide on a winner), but if you place, you'll get a feature in the news. The current contest is a fanfiction contest of a xianxia called I Shall Seal the Heavens, which you probably can't enter unless you've read the xianxia, but most of the contests have general themes that any kind of writer can join in.
- Be aware of the reader base. It is majority male, mostly people who enjoy Korean/Japanese light novels, anime, and manga. They like action and adventure. This isn't to say that other kinds of stories can't enjoy success there, or that you should change what you're writing to suit the reader, but you can do small things like optimize your synopsis to appeal.
Like I said though, it's 90% update frequency. As long as your story is of high enough quality that people will want to click "follow" after reading a few chapters, all you need is enough exposure to get a decent number of followers, and the Latest Updates list takes care of that.
I've been writing a lot about RRL recently... Sorry if anyone finds it spammy.