The majority of what I've sold has been boxes which aren't the easiest to "dress up." So what I've started doing is using one of the boxes the customer orders to hold a small 3"x5" notebook that I make from the chipboard scraps that are from making the boxes. I add tissue paper and ribbon (in the green that is in my banner and cards) and make it look like a gift, instead of a boring box.
I also include a handwritten thank you, which I write on one of the note cards that I sell, and my business card with a coupon code. Most everything has my custom stamp on it.
I'm trying to create that "opening experience," but I haven't had many sales so I can't yet tell if it's working. I hope that it is, but if it isn't I hope that the customer at least recycles what I send them.