Hi Michelle! You have some truly fabulous work in your shop!
The first thing I noticed was your titles. Some of them start off with names, like Creative Explosion, and these are very important words for search. The first few words in your title will help Etsy's software decide if your items match a buyers search terms. Not many people will search for Creative Explosion, but a lot of people will search for Illustrated Print, or some of the key words Brittany mentioned.
There's a great resources I found in the Seller's Handbook for finding good key words. It's from Google, and you just type in a search term, and it will tell you how popular it is. I linked it below, hopefully it works.
https://adwords.google.com/o/Targeting/Explorer?__c=1000000000&__u=1000000000&ideaRequestType=KEYWOR...Best of luck!