As with most jobs, your salary is going to depend on where you are working and your actual job description. You will also find some variance between working for an in-house marketing department and an advertising agency or design firm.
On average, a CSD with a few years of experience can expect to earn from the mid-60ks and up. (Again, that depends upon where you live and work.)
If you want to increase your salary, you will try to broaden your skill set or knowledge base. For instance, if you know a lot about print but nothing about the Web, it would behoove you to take classes in that area. Or, if your knowledge of print is limited to, say, offset printing, you might want to expand your knowledge of printing and learn about rotogravure. Or, taking it one step further, you might want to learn about direct mail - which might be a natural extension or application for printing.
In short, the more you know about other media - print, Web, broadcast, direct mail, interactive, etc., the more valuable you will be to your employer.