Business cards are much more than a convenient means to leave contact information.
First and foremost, your card must be legible. The most common mistake in business card design is overcrowding the front of the card. Include your email address and website URL if you can, but remember, a card that's too crowded won't be kept or read. If you need more space, print on the backside. What you do with your business card is almost as important as the card design.