Whether you are inviting a client to an event or thanking them for a referal a greeting card is a great way to build your relationship with your art collectors. It's also a great way to stay in touch with your clients throughout the different seasons and holidays. In certain situations it is a nice gesture to include a gift card for a meal in town or a fancy italian coffee.
It always feels strange to me when a a long period of time passes and I haven't had contact with key clients. They are a huge part of my success and I want them to be reminded of that even when they haven't just bought a painting. Nothing screams professionalism more than when you present your latest art buyer with a greeting card with your artwork on the front and some thoughtful words on the inside. A greeting card with a seasonal wish crosses out of the realm of professionalism and into the realm of being a grateful human being.
One of my favourite print companies is Moo.com . I really like them because you can print a set of greeting cards with a different image on each card in the set whereas most print companies would force you to order twenty cards with the same design on each of those cards.
Have fun making your cards!