There are dozens of these, take a look at them here.
Gmail understands boolian search queries, here are four that may come in useful: There are lots of other shortcuts to learn. Now you can use the following keys to get things done: If you use Gmail through the browser you can enable keyboard shortcuts in Settings>General>check Keyboard shortcuts on.
You must then scroll down the page to tap Save Changes. Here you can set your sign-off, and make a few minor adjustments, such as having it appear above the quoted text in replies.
