Bruce, when you create your image, you need be sure that your original artwork is at a high resolution, at least 300 dpi. For a business card, your image doesn't need to be huge, but you want it crisp. You don't want it blurry or to be able to see the pixels in your image when it's printed. If you're not sure how it will look when it's printed, zoom in on your image in whatever software you're using; it should stay crisp. You'll want to save it as a jpeg when you're done.
There are varying degrees of card services. For the lowest end, you can buy a BC card stock at Staples and print them at home if you have a quality printer.
Then there's Vista Print, which will get you a more polished look.
I've done both of these, but my favorite is Moo.
You can't beat the quality, and there are so many variations to give you and your product a unique look. Customers at my shows sort through my business cards to pick the one they want.