Create a New Message
To create a new message in Outlook, you probably click the New button in the Outlook toolbar.
If you'd like to save a few inches of mouse travelling, double-click on the empty space under the list of messages, as shown in the screen shot below. That will open a new message window for you.
If there's no empty space at the bottom of the list, or if your hands are on the keyboard, press Ctrl + N to create a new message.
These shortcuts also work in the other areas of Outlook, such as Contacts, Tasks and Calendar.