You have 20 viewers, I'd say that's pretty good so far. I told myself to give myself 5 years before getting into any high numbers (say 1000 subscribers). As that seems to be the average minimum time it takes for people to get that kind of popularity. Look around at some of the big shots and look at their trends, when did people start to really begin commenting on their posts, maybe even ask them when they noticed the rise.
I've heard some people made bigger popularity by expanding their content to other sites (you loose track of your readers yes, but there are more of them, only problem is you have to update everything all the time *points at self * ). Best thing you can do is spread by mouth, go to a convention, getin a conversation, and shove it in their face. They might just like it XD.
Make friends in higher places or even in lower places. If those in higher places like you or the fanwork you've done for them they might just promote you on a random post that will direct a few more viewers your way. Talking to people who are in the same situation as you might just get them to stick by your side.
You can also go down the route of trending popularity and memes (personally it's not a favorite route of mine, but I've seen it work countless times). Doing fan art, crossovers, popular themes gets people to find it easier (with the help of hash tags). People on sites like tumblr eat up NSFW subjects (many a liberal artists on that site) but that isn't your type of comic. You will loose the originality of your characters, but that's fan service for you. Look on SmackJeeves' most popular comics, you will find 60% of them allude to pokemon, videogames, internet cats, and yaoi.
But, what you can do, if you do not want to do that to your own comic, is that you can make another comic that focuses on more popular subjects. A friend of mine has a character on tumblr based on My Little Pony. Her fan base has grown tremendously because of it, and she uses that as a crutch for her original comic character, for the 10% of followers that go beyond to see the comic she initially started.
I'm actually trying this technique myself with my side comic "Artist Confessions".
I have less viewers than you currently so perhaps it is not my place to give advice, but I hope it's helpful
~Myl
