Step 1: Create a brand new document of a suitable size with a single background layer. Now add in the picture you want to mask as a layer above the background.

Step 2: Zoom as far into your creation as is comfortable (400% to 1600% is usually the charm), and start to draw a path around the outside of your object with the pen tool. As a general recommendation, try to stay just inside the edge of the object - this way you will avoid including different coloured edge pixels in your final image and get a much cleaner result.

Step 3:  Clicking and dragging when placing your points will allow for smoother and more natural curved results than just clicking and placing straight lines. The pen tool is a hard tool to master, though, so just keep practicing. When you have a path all the way around your object, join up the first and last pen anchor points by double-clicking the first point you placed - This will complete the path.

Step 4: Using the direct selection tool, right click on a line in your pen path and select the option to 'Create Vector Mask'. If you have the object layer selected and have done everything correctly, you should now have an image isolated from its background. If parts of your mask don't look right, just go back in with the direct selection tool and adjust your pen points accordingly.

Step 5: Now all you have to do is add a funky background, the odd layer effect here and there, and you have your finished result! There, that was easy, wasn't it?