No real way of getting more subscribers, still trying to find the answer myself. Relate-ability towards something that people already know (lore, re-told tales, mythic backgrounds etc) seem to start off well I've noticed. Original original stuff such as involving strange species, etc (if you're going longstory form) doesn't do very well since, well, how would readers look up something they've no idea exists/ or heard about?
You can try some really intensive networking, as in personally trying to talk to and get to know every community member out there and appearing in every comment section of every comic with an eye-catching avatar so people will click on you out of curiosity after seeing you everywhere. It's a very very slow process but it got me my first 100 or so when I was starting out.
You can also use groups such as Skype, online forums, Webcomic Underdogs or #Webcomicchat (weekends on twitter) as platforms for spreading your work outside of Tapastic, but again, in things like those simply shouting out your comic and link will probably not get you many followers, Sometimes people subscribe to you or follow you on other media just because they recall you were a friendly neighbor.
If you're out there for views and subscribers alone, ok... I'm not here to judge, feel free to take a look at some of the more successful or popular gag-a-day comics or whatever form you're looking at out there. They usually involve pop-culture references, parodies, fandoms, fetishes, whatever's grabbing the community at the time, and are often widespread on various social media sites (be sure to water mark your work somewhere where it can't be easily cropped off, I've had that happen to me once...) Personally such content gives me no joy creating it, but if you enjoy it and it just so happens to be something that the community your comic dips into is digging, you should be good to go. (Honestly look how many subscribers fan-comics of say Steven Universe Fnaf and Undertale get on tumblr... makes sense though because the story has already been widespread and acknowledged).