SEO: How to Super Search with Advanced Operators
I use advanced search operators all the time when working with larger Shopify stores. They make it very easy to dig through all the results.
If you haven't learned about them yet, Jill Kocher Brown has an overview on them.
Tips for changing Shopify themes without breaking your store
Tom Davies covers what you need to worry about (and what not to) when you change your Shopify store theme.
One thing I'd add to his list: watch how your current and new theme creates the urls to your product pages. It's easy to not notice them change but if they do, you could cause a severe, but temporary drop in your organic search traffic.
Safely get more Google traffic for your Shopify store
Google's Rich Snippets will help you grow your Shopify store by sending you more traffic for free. Learn how you too can get Rich Snippets for your store.