There are four main functions of a business card, in designing your own business card you will need to ensure it effectively achieves all four.
A first impression
Business cards can help you make that ever-important first impression a good one. Not only is handing over a business card a powerful professional gesture, it is a great way to end an interaction in a clear and certain manner.
A lasting reminder
A business card provides a physical reminder of both your contact details and the interaction. While some people believe that an electronic exchange of contact information is more efficient, a business card is not affected by technological glitches, it is also less likely to be forgotten about, as the recipient will have to later move your card from their wallet or purse.
Handing over a business card will make you (and your business) seem more credible. By physically stating your information you suggest that you are stable and professional.
Your business card will be handed out to prospective clients; it may be displayed on a counter or thumbtacked to a bulletin board. It is a point of contact with your client and it is often the first point of contact, so it needs to sell your business.
Is it simple and clear?
Business cards with too much information, or hard to read information are likely to overwhelm the reader and thus be ignored.
Which of these would you prefer to be handed?