Your business card is super important.
It is often a prospect's first impression of your company's image.
You don't want to mess it up.
So to help you avoid that American Psycho moment (if you don't know what I'm taking about, search for American Psycho business card scene on YouTube), I've assembled a few helpful tips.

1. Hire a graphic designer.
   
2. Use a highly legible font (and use 2 fonts at the most!).
   Usually a nice simple sans serif or serif typeface is best.
   Try to stay away from decorative or script fonts unless you know what you're doing, and please, for Pete's sake, don't use Comic Sans!
3. Keep it simple.
   Don't try to put every piece of information on it.
   Logo, your name, your title/position, contact info (phone number, fax, email, website address, twitter name), maybe a slogan, maybe services list, that's it.
   
4. Incorporate lots of white space.
   Let the bits of information breath.
   
5. Hierarchy.
   The most important components should stand out the most (ie.
   be the largest/boldest, have the most white space around them, etc.
   ).
   The typical order of hierarchy is: logo, name, services or slogan, contact info.
   Naturally, there are exceptions to this.
   
6. Use the back side.
   Why waste all that real estate? Do something creative on the back, make it an expression of your company's identity.
   
7. Spend a little extra on good stock.
   A nice heavy card stock stands out in a stack of typical flimsy cards and feels like quality.
   
8. Consider using a unique die cut.
   Rounded corners are always nice and prevent your card from getting dog-eared.
   Maybe cut it in a shape that says something about your product (eg.
   if you're a food company, why not have a bite taken out of one side?).
   But always make sure your card fits in a standard business card holder - you don't want it to get lost or thrown out.
   
9. Consider special printing techniques.
   Spot UV/varnishes, embossing, letterpress, foil, etc.
   can really add a special touch and make your card stand out.
   
10. See Tip #1.
    

Of course, these are just guidelines.
There are no hard and fast rules in design, and plenty of designers break these "rules" to great effect.
In reality, there's no substitute for the hand of a professional.
If you can fit it in your budget, do it.
You won't regret it.
However, if things are tight and you can't afford to hire a designer, follow these basic guidelines and you'll be well on your way to a better business card.