The standard routing maxims of "outsided cut = counter-clockwise" and "inside cut = clockwise" just don't hold up too well in the curvy world of guitarmaking. Here's how I think when making router cuts (from above) on compound curves: always go downhill. On a guitar body, the bouts are the "hills"; so, from either lower bout you'd route toward the waist and toward the tailblock. From either upper bout, you'd route toward the waist and toward the headblock.
Hesh, for your headstock, think of the peaks of the wings as the "hills" and route from there down to the nut (on either side), and along the sides until it starts to flair out again (from the photo, I can't really tell if it does flair toward the top. If it does, stop at the "valley" and start over from the other "peak." If it doesn't, you're good to go along the whole side). Now, here's where it gets a bit confusing. The curved top of your headstock could very logically be thought of as a "hill," but you should always route "down" end-grain (the same reason the tail-block area of the body isn't a "hill"). So, in this case, the upper wing peaks are the "hills" and you should route from there to the center-line. Basically, the whole concept works around knowing where your end-grain is, and finding the "hill" that leads down into it.
Why does this work? Well, it's easy to imagine why routing into short grain could grab it and pull out the wood ahead of the cut because wood wants to split along its grain lines. The cutter can hit a softer grain line and literally push out a chunk of wood before it can cut it. So, since the cutter is always turning the same way (clockwise, when making a hand cut), how does changing the direction of the feed make a difference? Because if you use a climb ("downhill") cut, the wood that might have been chipped out by the spin of the bit has already been cut away. Hard to explain without a diagram.
How come it's called a "climb" cut? Because when you move the router in the same direction as the spin of the bit (clockwise, on an outside cut), it happily grabs the wood and wants to "climb" in the direction of the cut. That terminology made it difficult for me to grasp the whole concept until I started thinking of the climb as "downhill."  Warning: ALWAYS concentrate mightily when making this cut, because the router can VERY EASILY jump out of your control and ruin your work, ruin your router, or ruin your body parts! 
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. My reccomendation: get a piece of scrap wood (any real wood will do, something splitty is good), and try cutting a few test-headstocks.