If you're great at writing or art, you might be able to earn some money creating graphics and/or prose for greeting cards. This page has a huge list of 47 companies that are regularly seeking submissions from freelance writers and artists for the greeting cards they sell.
Greeting card companies often hire freelancers to both write for and provide the artwork/photography for them. For tips on how to be successful, check out this article from the Greeting Card Association for writers and artists. Then, check out the links below for companies to submit to: Writing Greeting Cards American Greetings – This company does …
Did you know writing greeting cards is a real profession -- and pays an average of $50K? Here’s which Hallmark jobs are available, plus a few other opportunities. - The Penny Hoarder http://www.thepennyhoarder.com/get-paid-to-write-greeting-cards/
How to Sell Greeting Card Designs: 1.Research the market. 2.Evaluate popular niches. 3.Choose whether you're going to create handmade cards, design and print your own cards or hire a printing company to print your designs. 4.Purchase an inkjet printer if you plan to print your own cards. 5.Design several greeting card prototypes, contact locally owned stores in your area. 6.Sell your greeting cards online.