One of the most painless ways to increase your site traffic is to analyze your visitors and see where most of them originate.  You can take that information and use it to:

Identify a demographic
In order to please your readers you need to know who they are.  Identifying your key traffic points is crucial in understanding your traffic and catering to it.

Identify likely advertising spots
Now that you know which sites bring you traffic, you can advertise on like sites to increase said traffic.

It’s relatively painless to take a look at your traffic and see where it originates.  If you aren’t doing it on a regular basis, you might consider taking a look at your site’s log to gain insight into your traffic patterns and visitor’s origination.