Raise Your Rates
Charging more is the easiest way to make more money. You should raise your rates at least once a year to keep up with inflation. However, few writers do this. I know writers who haven’t raised their rates in the past five years. This is silly, you’re learning more and you’re worth more to your clients because you’re creating additional value.
via www.fabfreelancewriting.com
The most common question I'm asked by aspiring writers is "how much do I charge?"
There are no standard rates for freelance writers of course, so what you charge is up to you.
Once you have a stable of clients, be aware that your rates are not frozen in time. I've noticed that most freelancers are reluctant to raise their rates. As I point out in the above article, your rates should at least keep pace with inflation, so raise them once a year. Chances are your clients won't even notice.