Hi everyone!
I've received a few convos asking about keywords vs. tags. Let me explain.
Tags are directly related to Etsy Search - Google (and other search engines) don't weigh tags too much (if at all), so if you are thinking about optimizing your shop for search engines - you should be thinking about the keywords you use in your titles and the very first paragraph of your item listing descriptions. More info on that here:
http://www.etsy.com/help/article/247
Tags on etsy must be single words or common compound words. I'll give you an example: "sterling silver" is a fine tag. However, "textured silver" would be two words together so that should be two tags. "Aqua blue", is fine as one tag but "red blue green" is a no-no.
I hope that helps!
Best,
Danielle