I often read or use these resources to get tips and advice from other greeting card designers. I have found them to be helpful in my greeting card and design business:
GREETING CARD GROUPS
Linkedin Greeting Card, Stationery & Gift Industry GurusNetworking links of sales, marketing, product development and sourcing people from these related industries and to help entrepreneurs gain access to industry knowledge and 'how to's."
Greeting Card ProfessionalsThe worldwide default network for publishers, distributors, designers, buyers, developers, (online) retailers and anyone else relevant in the business. Feel free to join and don't forget to invite your colleagues and business relations.
Greeting Card ProfessionalsThe Independent Greeting Card Professionals Association is composed of working professionals--and beginning professionals--who create and sell greeting cards retail or wholesale, at craft fairs or trade shows, or via the Internet. Members produce work in a variety of greeting card genres.
ART LICENSING GROUPS
Art of LicensingA LinkedIn networking group dedicated to Artists, Illustrators, Designers, Product Manufacturers, and Licensing Agents in the ART LICENSING industry.

Yahoo Group Art of LicensingA SPECIAL FORUM dedicated to Artists, Illustrators, Designers, Product Manufacturers, and Licensing Agents in the ART LICENSING industry.
MORE GROUPS TO CHECK OUT
Escape for Illustration IslandIllustration Resource Website and Podcast devoted to helping artists to connect and communicate with fellow creators.
ScbwiSociety of Children's Book Writers and Illustrators
Art & Design Loungehelp Artists and Designers advance their careers and business goals helping them make vital new business contacts.
Stationery TrendsFacebook group for the magazine focused on the products, designers and inspiration that make up the stationery, greeting card and gift industry.
TWITTER RESOURCES
Stationery ShowLeading trade show for the social stationery industry.
SurtexSelling and licensing art and design for every product, every industry.Greeting Card Designer Tips and resources for Card Designer and Writers .* Am I missing something? Let me know. I'll add it to the list. Or leave comment below. *