1. Open your artboard and write text using the shortcut key "T" or simply by clicking on it of any color (Text color doesn't matter for the outline).
2. Right-click on the text layer and click on "Blending Options"
3. Select "Stroke" and set the positions to "Outside" and increase or decrease the size as much as you want your outline thickness to be, also the color in the stroke panel will be the color of your outline.
4. Hit "OK" and just below opacity, set the filling option to "0%". and you are done