I use baskets that are a little bigger than the width of my greeting cards. I have the cards organized by different topics and another basket for envelopes. I also have a basic round basic to put some of my craft items like glue and tape.
The clear box in front has labels with my Etsy shop link that I put on the back of my greeting cards. I also keep my business cards in here.
These baskets are also good for displaying my cards at craft shows.