Did you know GMail from Google has all kinds of easy-to-use “operators” that you can use from the Gmail search box?
One of my favorites is an operator that let’s me find all the UNREAD email in my INBOX.
That command is: label:inbox is:unread
Here are a bunch of other operators you might also find useful if you use GMail.
http://support.google.com/mail/answer/7190?hl=en