I'm new to this, so take my advice with a grain of salt! However, in my 6 days of writing Hubs, I've racked up over 200 views, so I believe I'm doing something right.
The first thing I'd say is to make sure you're writing about things you truly care about and understand. The best promotion you can get is good content, because if you're able to fill a niche by meeting a need that's not being met already (or meeting it in a way that it isn't already being met), your material WILL be seen, even if only by your fellow Hubbers.
I've had limited success with social media; so far, Facebook hasn't really given me any traction but I'm starting to see things trickle through from Twitter. I'm writing a guitar-related blog and I play in a popular New England band, so I think a little crossover traffic is working in my favor.
But so far, other than HubPages itself, the single biggest source of traffic for me has come from submitting my Hubs' URLs to StumbleUpon.com. It's not exactly been a deluge, but if I leave a Hub up for a day on its own, it might garner 10 views from HP initially. If I put it up on StumbleUpon the following day, it's almost guaranteed to accrue an additional 20 hits over a day or so. Again, not huge, but it gives my views a shot in the arm almost instantly.
So, good luck to you in your promotional efforts! I hope this information helps.