I've been pretty busy and haven't stopped by the forum for a while, but I just wrote this for another WAHM and thought someone here may benefit from it also. I'm editing out my personal details and just giving you the 411:
Many people have discovered ways of producing a part or full-time income by specializing in Search Engine Optimized (SEO) writing. If you're not familiar with it, it's essentially writing in such a way as to include keywords that people commonly search for on a particular topic. SEO writing is not difficult to learn how to do and it's a skill that's in high demand. Pretty much anyone who does business on the web needs SEO content to attract traffic to their site.
(If you're interested in learning how to produce this writing style here's a very simple article on the basics written by Yuwanda Black: How to Write SEO in Four Easy Steps. You may also want to Google this author, as she is all over the web and a great source of information.)
Before getting started, it helps to write and publish a few SEO friendly articles just to get the hang of it. Doing so helps you get comfortable with this style of writing, builds skill confidence and will help you build samples that you can offer to clients to prove that you can get the job done. Associated Content doesn't pay a lot of money for articles, but it's a good place to practice and even get some feedback.
As you research the field on your own, you'll hear talk of content mills. Essentially, these are websites that pay writers to create SEO articles for various websites. Some offer a flat rate or a flat rate plus residuals (meaning you earn money each time someone reads the article or each time someone clicks on an ad that accompanies an article). And some only pay residuals (these are also known as revenue sharing sites). Some content mills are better than others in terms of quality and pay. Here are a couple that I can comfortably recommend:
wiseGEEK ~ Pays between $10 - $14 per article. Payment is by PayPal within two days after five articles are written and edited (unless they're backlogged, however, most payments are issued on the same day or the next day in most cases). wiseGEEK can be a little hard to join as a writer, so be sure you have a clear understanding of SEO and that you submit polished writing samples when applying. You'll have to go through a three-part testing phase before being hired, but you'll be paid for any articles you submit during testing whether you're eventually hired or not.
BrightHub ~ Pays $10 per article upfront and has a pretty good residual program, so you'll continue to earn on published articles long after you've written them.
There are a ton of others mills (a main favorite for many is Demand Media-- they're good, I'm just not a fan so maybe one of the other writers here can fill you in), but these two are at the top of my list in terms of payment, reliability, etc. While mills don't pay a whole lot, think of them as part-time or supplementary income. The real money comes from private clients who hire you to write for them. Or, even better, learning how to operate your own sites and writing for yourself (you make money on your own sites from ads, affiliate revenues, selling products, etc.).
For higher paying writing jobs, take a look:
...And don't forget that Mothering also uses freelancers!
A couple of good places for you to visit to learn more are:
http://www.wahm.com/forum/wahms-who-write-46/ (if you're interested in other ways of making money while working from home, this site has lots of other sections for all types of business models, too)
http://www.warriorforum.com/ (not limited to freelance writing, but an excellent place to learn how to earn an income on the web, in general)
http://www.smartpassiveincome.com/ (A general passive income site, but the owner gives good info without constantly pushing you to buy something like so many similar sites do)
http://www.workathomemomcenter.com/freelance-writing/ (Another informative article on how to get started freelancing. This site also has information about other work at home jobs)
http://www.problogger.net/ (Darren makes millions by blogging and talking about blogging)
http://inkwelleditorial.com/about (Yuwanda is the author I mentioned earlier. She freelances full time and shares lots of good info on her site and elsewhere on the web)
http://www.chrisblogging.com/ (Like Yuwanda, Chris Bibey is another great source of information for learning to freelance online)
As you'll find visiting these forums, sites and blogs, freelance writing is a 100% work from home gig. The hours, days and times you work are completely up to you, as is the amount of income you choose to make.
Do not fall for the okey-doke that you need to buy a bunch of ebooks and special reports to figure out how to earn a living writing. Don't get me wrong, some of them are very informative, but none of them are necessary to get started. All of the information shared here is enough to launch a freelance business.