Another good trick:
Ad mask (Klick the image and the open Layers panel. Bottom of that panel is mask button)
Ones you have the mask, take the Gradient tool (or hit G in kbord). Make sure you have the mask selected instead of the image (layers panel again).
Now select fill. Options are from black to white. All Black is equal to 100% transparent.
Ones you have the edge of fills selected, you can start makeing nice fades.
Try it. You love the options that this tecnigue gives you.