First, you need to decide what kind of budget you are working with. If you have no budget, then you'll need to invest your time.
Writing articles is the most effective way to increase your search engine rankings which will definitely get you more traffic.
I would also recommend creating a blog, as well as a forum, and posting regularly on your blog, as well as visiting forums on your topic.
Some forums will allow you to advertise. Others won't. Even if they don't, include a link to your site in your signature file.
Submit your RSS feeds to all the feed directories. This will also help you get your site indexed. You also want to make sure that you submit to Alexa. This will tell you a lot about your site, rankings, who's linked to you, etc.
As for getting traffic fast, and if you have the money, write and submit a press release to PR Web and pay the $80 that will get you on the top news sites.
Press releases are very effective.
The internet is content driven. People want information. They don't want advertising constantly shoved into their faces.
Content is an excellent way to market, and there's no one perfect solution. It takes a little time, but it's definitely worth it.