Keep in mind that the intitial "surge" of traffic is often internal (on the site i.e. HP or WZ authors reading yours stuff- your "fans/followers"), so that likely accounts for that traffic you're experiencing.
Readership is about having a well written portfolio of articles, covering a large subsection of concepts/niches. Also it takes time for your articles to season and beat out all the new stuff and to become syndicated (backlinks, people sharing it with their reader base/friends, etc...). To speed up readership you will need to promote your articles and it's about hitting the right trends at that point.
The best advice I can give is to just write write write and give it some time to season. Don't be impatient, you never know what article will start trending out of nowhere and start to generate a buzz, that buzz is awesome when it yields enough backlinks or link on the right highly trafficked site to make that article stay popular- these would not be trendy topics but rather timeless topics that trend and get attention due to a variety of factors from news happenstances to just the right person saw it and just happened to have a huge reader base they want to share it with.
I wouldn't even worry about earning or getting a lot of readers before your 300th or so article, by then the first 100 likely will start seasoning and like generations, each will sprout out and synergistically it should bud out and create article pollen :) (backlinks)...
At first your job is merely to learn to write better, build better articles, learn monetization techniques, and write write write- it's much easier to deal with promotion when your work is seasoned and perfected.
If you build it, they will come.