I highly recommend the quick mask. Actually, I use a layer mask, just so I can edit the edges later on if I change my mind - but this is up to you. Try this, if you do not have a steady hand:
The round head is the bane of your unsteady hand. Other than that, it’s mostly straight lines. Use the elliptical marquee tool to select a part of the head:
Press “Q” to enter quick mask. Start with a fairly large brush - I’m using a 22px diameter, hardness: 100% round brush). While holding the shift key, click on points between straight lines. Holding shift while clicking creates a straight line from point to point (sparing your unsteady hand). His face has a lot of straight lines, so this isn’t too hard:
Here’s a detail:
Above the green circles represents points where I clicked. The single black circle was the last click. Keep doing this for the edges. Don’t worry if it’s a little off. In the end, you’ll have a bunch of clean lines and you’ll only have to do a few touch-ups - here I touched up the hood a bit, since it’s a little curved. Don’t be afraid to use the elliptical tool again to precisely select curved areas. That’s it! I accomplished this in just a couple minutes:
There you have it: I pretty much just regurgitated what Lost said, tossing in some time-saving keyboard shortcuts that you may not have known about.