For the ones of you that don't know, and still try to optimize their SEO, I have a link here.
https://www.etsy.com/search-ads/keywordsYou can search keywords and see what they cost if you would have a search ad on Etsy. The more popular a search term is, the higher the price.
I find it's a good way to search by one keyword, and find appropriate two word keywords that way for your listings.
I hope this helps someone.
Happy Saturday!