The Position should be set to Outside and set the size to 3. Change the color to one that looks good with the original text color.

It should look something like this, depending on the colors you selected.

Now if we went to Layer>Layer Style>Stroke again, we'd just bring up the options to edit the original stroke. Instead, click-and-drag the text layer to the New Layer icon the Layers palette (or press Command-J (PC: Control-J)). This duplicates the text layer.

Now we need to edit the stroke on the lower, original text layer to make it larger. Double-click on the Stroke effect listed on the bottom text layer.
