I will like any picture or photograph on the card you'll select for me. As to the backside of the card: write whatever you want. And if you do not know what to write, tell me the title of a book you are very fond of or have recently read. Or let me know why you became a postcrosser. Or write about your daily duties, your town, your life. Or write a sentence in your language (with translation).
Looking forward to receiving your card. Thank you.
Danke für Eure Karten. (Thanks for your cards.)