Done. The first 40 items are in my shop now. I had prepared all descriptions and images for the upload already when Etsy provided a completely new guide for SEO for Google. So I read through this guide and then I had to re-work all my descriptions!
And not only the item descriptions. Relevant for Google as well are the shop title and the first part of the shop description. You have around 60 characters for the shop title (depending on the length of your shop name) and 160 characters for the shop description. And with these few characters you have to express what your shop is about. It should be catchy and it should contain words that people searching with Google are looking for! I did some keyword research but I think, I didn't really get that. So I mixed and matched the words around and hopefully it's ok like this.
However, finally I listed my first item on September 28, this lovely VW beetle.