I've been working as a copywriter for nearly two years. It's a part time job that subists my income from a full time position. Although I've had no formal training as a copywriter, work has been consistently feeding through via my website. I attribute this to keeping my prices low. This allows me to accumulate clients who will, most likely, want their content reviewed and/or changed at a later date. I also take on the occasional contract, gratis,for high profile customers, in order to expand my portfolio and gain some more kudos in the marketplace - hence, at a later stage, as and when I decide to go full time, I will be able to justify the increment in my pricing. Including SEO work as part of my services has really helped, too, as this naturally sits alongside organic copy.
I would be interested to hear what other writers feel works well for them, as I am sure that there are holes in the approach that I have adopted! Does anyone have any recommendations/suggestions at all?