Korajuku, I really don't get all of the SEO stuff. The main things I've pick up are that the first three words in your titles are the most important, so think of things to word it that people may be searching for... and you look up on google words that are search more often to figure out what words to put in your tags. Listing the same words in your tags as in your title is suppose to help also.
Also looking at your shop, your shop announcement is a lovely welcome, but I guess google uses that the most to pick up your shop in searches. So the best way to get google to notice your shop is in your shop announcement to first describe the type of product you sell along with your greeting.