According to Kelly James Enger, author of "Six Figure Freelancing," trade publications are a starting point for freelance writers. They are traditionally easier to crack than national magazines and give you the needed clips to add to your portfolio. Often trade publications are regional, meaning they have links to your own community. It's likely you know someone who works in an industry that has its own trade publication.
National magazines are major newsstand magazines or publications you see at the grocery store. There are thousands of national magazines. Some only accept submissions presented by agents, while many others accept queries from freelancers. It's always best to query the editor about an idea before wasting your time writing an article whose premise could be radically changed by your editor. Reading several issues of a magazine you're interested in will help you get a feel for the type of work they're looking for.
If you're writing content to generate your own income, there are dozens of sites and article directories you can use. Some require your articles to go through a review and editing process and some allow you to publish on demand. Popular sites include eHow, Suite 101, Helium, Article Base, Associated Content and Examiner.
Most companies have newsletters, both for their employees and for their customers. These newsletters often need interesting, relevant content and your article might fit the bill. Online newsletters and mailing lists can also be potential article markets.
Newspapers used to be the primary place where people published articles. Newspapers have paid staff, but there are still some newspapers that accept submissions. While it's more likely a newspaper will look to staff writers for content, your article may be able to help fill a gap. Be sure to ask the publisher to post your article on the newspaper's online edition.
You can publish your own work on your own blog, or you can query blogs with millions of readers to see if your article is a fit. Some blogs have as much or more readership as traditional print magazines and newspapers, so they're definitely a great way to get your work out to a large audience. Blogs are gaining recognition as important sources of information and popular posts are often syndicated to larger publishers.