Use the magic wand to select each outline/edge and apply a stoke [ edit>stroke....] to the selection, if the image is low res ( 72ppi ) you may see stepping around the lines.
 you can adjust the width of the stroke to give you the style you are looking for...
when i select the outlines, it only selects little parts of it
When you select the magic wand there is a lil box called tolerance in your top tool bar. 1 is low tolerance and 100 is full tolorance. You have to play with it to get the right balance but often using the magic wand will result in jagged edges and adding a stroke to it would make things worse unless you wana spend hours cleaning up the image.
Your best bet is to look up a tutorial on youtube on how to trace an image with the pen tool. Recreating the lines from scratch is easy when a lil practice with the pen tool. Then you just set a stroke to your lines at your desired width. This is the only way you should be doing it if you want any type of quality.