Angie,
In order to come up with a good marketing plan for this company, you need to consider what the company sells, who its target audience is, things like that.
So it's impossible for us to say whether your ideas - DM and articles (or press releases?) would be a good plan for them without knowing that.
It's hard to believe they could even have a business without doing any marketing whatsoever, but then again, I've had clients who say they get all their business through word of mouth (these are mostly holistic practitioners).
We live in a culture where any of us can call ourselves a copywriter or a marketing consultant, and we're encouraged to do so. But you should be sure to study not just copywriting but also marketing. A couple of good resources:
Thirty Day Challenge, which just started - it's a great time to get into it.
The System Seminar - and that one just ended, but that's okay. Just get on Ken McCarthy's email list and you'll learn a lot about marketing.
It's hard and scary to start out. I sense that you're afraid to learn by doing, but I think that's the only thing you can do.
Keep studying marketing and keep working with clients. It sucks to learn by falling on your face, but it's an unpleasant and necessary step on the path (actually I think it there are such slippery spots all along the beginning of the path, quite a few in the middle, and I suspect there are even some at the end).
Continue to study copywriting and marketing and continue to do the work you're doing.
I hope this is helpful.
Janet
P.S. Have you checked out the Warrior Forum? It's all about Internet Marketing, including copywriting. You might not meet as much sarcasm and hostility there.
www.warriorforum.com