I write my title, then use all the words in tags. Also, using more than one word in tags is essential. I looked at one of your listings and saw that you have a lot of them. Maybe consider getting rid of 'reusable' and replacing it with 'reusable coffee cozy' Also, I'm not sure if this applies to commas, but I've read that you should put a space between punctuation and words. like: Easter Coffee Cozy / Cup Warmer / Reusable Coffee Sleeve / Pink Easter Eggs
That's just what i've learned form stalking SEO & relevancy threads. Love your shop, by the way!