Your cards are very charming, and Janet is spot-on about your tags. Rework those babies!
You may also want to come up with one consistent way to display your cards for the thumbnail image. It needs to be close enough to make out the design, but also show the entire item, well-lit and against a contrasting (but not distracting) background. For your cards, I think the style of the second photo here:
https://www.etsy.com/ca/listing/211768094/holiday-card-t-rex-christmas-card would be ideal for the first photo slot, and then I'd crop the listing thumbnail so that most of the thumbnail is taken up by the card. You should also try softening the light by using several lights at different angles, bounced off white sheets (or build a small light tent to put over the area).