I have worked as a graphic artist for the last 10 years, mostly doing newspaper and direct mail advertising production. I don’t have a design degree, but did take graphics courses while in college and did production work for the school newspaper while enrolled. So you can get work out here without the degree. Having said that, an awful lot of job listings insist on a BFA or better. As was noted above, a lot of these jobs get filled through word of mouth; if you don’t have the degree, that might not be a hindrance if someone who knows your work can put in the good word for the right position.It’s your call on the degree, or any other certifications; just remember, it will take time, and can get expensive.
As for practical knowledge, I suggest learning all the Adobe programs inside out. Really be an expert, not just someone who’s done light photo touch-up work for his own personal projects. Be especially good at Illustrator–people don’t seem to know nearly as much as they should about using AI. I would also recommend getting as much knowledge as you can about QuarkXPress; even with InDesign making a lot of inroads, QXP is still the standard in many design shops. You’ll be lost if you walk into a studio knowing the CS programs in and out but don’t know jack about Quark.
And, if you can swing it, I’d also recommend learning (if you haven’t already) the Macromedia Studio programs, particularly Dreamweaver and Flash. (Don’t worry so much about Freehand–I’ve never liked it and never needed to use it professionally.) Not only will it broaden your knowledge, it will also address the issue Knowed Out raised above: If you can have a web-based porfolio as well as hard copies, so much the better for delivering samples to prospective employers. The Macromedia website has some very good basic tutorials for Dreamweaver (and CSS styling, which is what you really need to know for web production).
And really, portfolio is probably the crucial matter. If you’ve got a killer portfolio with a lot of great projects to display, you’ll get hired somewhere whether you’re certified, degreed, or polka-dotted and striped.
If you don’t already have a great portfolio, you might want to pursue some freelance jobs first, use those to build a good set of projects, then try to find a full-time position.
So that’s my take. Good luck. And if you find someone who’s hiring, let me know–I sure am ready for a new gig!