Also, about clubs or organizations, please mention if you need to be sponsored for the organization, elected to it, or volunteer. It's not a big deal which it is, but it does define the activity better.
The most design I'd ever use (or have seen) is maybe a line of color down the side, or across the top or bottom.
ETA: I think the type of paper is most important than a design, such as Crane, Tiffany or such.
This is an example. One woman for whom I wrote a rec used matching notes to thank the women who gave her recs, then let us all know with the same matching cards.
I was impressed with her style!