You can increase your traffic by selecting tags so your hub show up in the "related hubs" section of other hubs. Additionally you will want to try your best to increase the hubscore of your hub. A great way to do this is by suggesting links to other hubs, linking to your own hubs, etc.
Some traffic will come from Google, but to really take advantage of this you need to be doing proper keyword research before writing your hub. I rely on hubpages itself to drive most of my traffic and I have been quite successful.