As you are probably aware, tags matter, because they communicate to your Etsy customers what it is you have to offer. When someone searches Etsy using the phrase "cherry red knee-high elf stockings," and you have exactly such a pair for sale but you only used a single tag, that of "socks," to describe it, this customer will sadly not be able to find you listing. And it's a shame.
But this need not happen to you!
Tip #1: Describe Your Colors Like a Writer - Do not, for the love of vintage, use only "blue" as a keyword when your item is the "aquamarine" or "cobalt" or "navy" or "pastel" version of blue. If you're having trouble coming up with the particular name of the hue and shade you want, Wikipedia (among other websites) provides lists full of them, usually accompanied by color patches. So use 'em. But leave in the more general color name also, just in case.
That's not just any green, it's olive. Oh wait. The shape is confusing me. Could it be mint?
Tip #2: Use up the Tag Space Like a Twitterer - Never use just one word in a tag. Always use a phrase. Because according to my sources on the Etsy forums, the more times you use major keywords, the better. So instead of writing "dress" and "day" and "light" separately, write "light day dress." And then go on to add more relevant phrases containing the word "dress."
Tip #3: Think Like a Customer - As an Etsy shopper, there are times I will type in keyword clumps such as "pretty fairy-tale dress" or "cute valentines day mittens" or "romantic old-fashioned gold locket." So think about the way your customers might describe something. Who are they? What do they want? And include adjectives such as "steampunk" or "boho" or "shabby chic." Also, if you think people might be searching for your shop name, you could include it as a tag on a few of your items.
Here is an example of one of my first of tagging attempts (see the listing here), and my current tags for the same item:
It's not as though the first ones were that bad, but based upon how much better my visibility has been in the Etsy search after implementing the above tips, they did help. This particular dress even was featured in a cobalt themed treasury on the front page of Etsy!
I hope this helps some of you out, also. =)
Sunshine and snowflakes,
P.S. Have anything to add? What's worked for you?