Here are a few things you can not leave off your promotional item:
1) Contact Details and Web Address: These are extremely important as they are you first point of contact Make sure that these details are correct and can be easily read.
2) Your logo: It is how people recognise you. If you do not have a corporate logo, use an image or mascot that best represents you and your company.
3) Have a good or catchy slogan: A good slogan is sure to keep you remembered in your future customers mind and is a winner in marketing.