Keep publishing good hubs! If you go explore the different categories of hubs, you'll see that there are thousands of hubbers following specific topics, so whenever a new hub is published in a topic that they follow, they receive a notification in their email.
If your content is good and your titles are interesting, you'll pick up new followers with every hub you publish.
Follow that up with reading and commenting on other people's hubs too -- and following them, if you like their hubs -- and you'll acquire a large following.
Consistency is important, though. Whenever I publish hubs regularly, I pick up new followers without even trying. But during periods where I was missing in action for weeks at a time, my views would fall and I would even lose a couple of followers too.
This past week I published 5 new hubs and picked up 11 new followers. I didn't go to them. They came to me. So just keep publishing hubs.
But keep in mind, if you're trying to earn money here, you can do that even without followers. As long as your hubs rank in Google, you'll do fine. In fact, search traffic is really the key to making money on HubPages.