You can use Keyboard shortcuts in Gmail to save time and energy. First, you need to enable shortcuts in your Gmail account. Click on the settings tab at the top of your browser window and choose Mail Settings. Enabling Keyboard shortcuts is the third option down. Scroll down and click Save Changes. Click back to your Inbox.
Hit C to compose a new message. Hit J or K to navigate between messages, and hit Return to open one up. You can also navigate between messages using J/K when an email is open. To navigate back to the Inbox hit G and then I.