Evernote revisited a topic recently all Evernote users should periodically review : the Evernote Search Syntax.
If you don't know about how to search Evernote using their powerful grammar, take a few minutes to read the post and play a bit with what you have learned.
It will increase the value you get from Evernote. I'm a big advocate of putting almost everything in Evernote, but the value of the tool is getting back the notes you need. The tips in their blog post will help you do that.
The full search grammar for Evernote is documented in their Developers pages.
I remember how thrilled I was to discover the predecessor to that page. I wrote about it starting back in 2009.