Do you realize that your business cards tell customers and clients much more than just your name, your business and contact information? Your business cards are actually similar to your sales representatives. They tell about your business, your expertise and if they are good enough, they will be able to bring business for you.
Just like a real sales person, if they are not equipped with a good sales ability and good product knowledge they will not perform well. That is why you need to equip them with those tools.
The challenge is how to get those things into a physical card? Maybe this would help.
First, I insist you to use good quality stock to print your business cards. If you use cheap-low quality stock, they will give bad impressions for you and your business, so I recommend and insist you to use good quality ones. You can add your company logo and you can tell about your business and your expertise but do not make it too much. Keep it simple and clear, and make sure it is written in readable fonts and colors.
Then you should state your differentiation. Tell your difference from the other competitors. Maybe you can offer the cheapest price, or maybe you offer the widest product varieties, or maybe it is your discounts, whatever your offers in your business that make you stand out from the crowd. You can add that difference with the shape or size of the card. You can use smaller size card or rounded shape card than squared one. You do not have to be the best. You only need to be different.
The last tip is to always bring your business card wherever you go. You will never know where you can meet a prospect or a client. If someone asks for your phone or mobile phone number, give your business card instead.