The bad thing about these kind of websites is that you don't see any money for awhile. It could take months before you reach the payout minimum, but the good thing is that once your articles start earning money they normally earn that amount, or better every month. I've done some research and have heard of some people making $200 - $300 a month from any individual site, and I've even heard of people making around $1000 from it per month. Of course, these writers have been doing it for quite awhile and have written a lot of different articles, not just one, or two.
If you are not sure about what to write about, just give it time and make a list. Sometimes ideas will pop in my head at random times and I have made a list on my laptop so that I don't forget what they are. Whenever I get ready to write I just pull the list up and choose a topic from it to write about.
Just remember not to give up if you don't earn much the first few months, it takes time and patience. Use your key words, and promote each and every article on places like twitter, digg, stumbleupon, myspace, facebook, any kind of networking website. Promote them on your blogs, tell your friends about them, promote, promote, promote.
There are two other websites that I write for as well. I stick mainly with the pay per article sites during the week, but try to write at least one article per week for the residuals. I will be writing about the other two soon.
Here are some of the articles I have written on Ehow so that you can get an idea as to what your articles will look like and what ehow is about.
How to Videos & Articles: eHow.com
*If you already write for ehow, feel free to add me as a friend!*