I have discovered a few things that help.
I have 6 fics posted on AO3, and I don't use ff.net. The one with the lowest hits/kudos is the one I have never promoted and it's the poorest one I have posted.
All my other works have 200+ hits. I'll summarise from least to most hits:
My multi-chapter has 224 hits, 15 kudos and 16 comments. This was mostly promoted only on my Tumblr, here and on Twitter, so to people who were already in my 'circle'. It's also a sad and depressing fic which won't suit everyone.
Next is my Secret Santa fic for Marva which has 234 hits and 22 kudos. Again, posted only here, on Tumblr and on Twitter. This one is marked as part of a 'collection' in AO3, which encourages those who enjoyed other fics in the collection to explore the rest of them, so I may have got some views through other people's SS fics.
My first fic (which became a draft of the first chapter of my multi-chapter fic) has 275 hits and 23 kudos. I think this one is only higher because I was so nervous/excited that I encouraged everyone I knew to go read it!
I Should Retire was written for the "No Shame" ficathon which came about thanks to Caitlin Moran's abuse during the TEH Q&A session. It has 350 hits and 27 kudos. Again, this was posted to Tumblr, Twitter and on here but is also part of the No Shame collection which includes fics from some fairly well-known fandom authors like EarlGreyTea and Flawedamythyst. I probably got some click throughs from the collection.
My most successful fic is Hamartia, which is my missing scene fic from His Last Vow. It has 968 hits and 78 kudos. I posted it on Tumblr, Twitter and here, but I also submitted it to sherlockbbcficrecs.tumblr.com for their review and would have gotten a lot of click throughs thanks to their post. Also, the subject matter probably encouraged more views as a lot of people were looking for 'fix-it fics' or missing scene fics after Season 3.
So, I guess, from my measly experience, getting a fic recced/reviewed on a fic rec blog definitely helps!
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I dislike being outnumbered. It makes for too much stupid in the room