Insetcards can be used in a variety of postcard advertising and marketing campaigns, from the one-time mailing to long-term, multi-product promotions. Consider the opportunities that will not only reach your customers once, but that can keep your customers involved in your business. Stay in touch and give them the gift of a collectible card with your name on it. Their repeat business will be your reward.
Creating value for the entire collection of cards and for multiple editions
The advertiser might promote an advantage to collecting all the trading cards within a set or a specific subset of trading cards (like the game Monopoly where you try to collect similar properties). The postcard advertising campaign can be built around those collections and how the owner can use them. Ideally, all collectors will want to collect all the cards from all the sets / editions.