
1) Increasing Traffic and Visibility: Easier said than done, but you have to boost your presence to get traffic. Exchange links with other sites, get your site listed in directories, search engines, and create meta tags. It can also be beneficial if to use trackbacks and actively post comments on other sites (note however, if you are spamming Google has some of the best email spam filtering software in GMail I have ever used and I'm sure they have a way to detect this built into their system).
2) Use the Web 2.0: The usual suspects, reddit, stumbleupon, del.icio.us, digg, etc. Word of mouth can drive people to your site without you doing much work provided the product is good.
3) Don't go Crazy with Adsense: You are limited to three Adsense "units" on your page but that doesn't mean you have to have other ad programs all over the place. Remember there is a point when your site looks like a billboard and people stop believing you are pushing out content for a reason.
4) Create Good Content and Understand that it takes time: You won't make Alexia's rankings overnight and it takes time to create a user base.
5) Include a Search Box: Searching is second nature for many people. I'd much rather type in a few keywords than slog through 10 pages of links or posts. If your information is hard to find people will go elsewhere.
6) If You Have a Blog use Technorati and Feedburner: I was suprised at how much traffic I received from Technorati once I started religiously tagging my posts. Feedburner is a good because it pings sites for you (see below), allows people to quickly find your feed, and lets you keep a rough tally of the number of people subscribing to your site.
7) Follow the Hot Zone: I'm not overly concerned about making a few extra bucks with this site so you will be able to see I don't adhere to this advice well. However, Google has created a nice "heat map" showing where advertisements typically fare the best based on where users are attracted on a website.

9) Get Some Data: Visit Statcounter.com and sign up for a free website counter. It's invisible and will give you an idea of what kind of traffic you have at your site and how people are finding your site. It may also give you ideas if a certain page is generating a lot of interest.
10) Optimize Your Ads: Visit Adsenseblacklist.com, the site will create a list of sites you can paste into the adsense block list. This list will clear out a lot of the sites that advertise on Adsense for a penny or two per click and are nothing more than a bunch of advertising links. If people are clicking an ad and leaving your site it might as well be for something they can find useful.
Links:
More tips at RealityWired , Problogger series, and tips "from a 12 year old"