Installing a hinge properly is easier said than done. If the hinge is not placed exactly where it should be, your door can be misaligned, creating problems such as an unsightly gap, or the door being skewed to the rest of the workpiece.
A great tip for if you are alone and need three hands to be able to install a hinge is to hold the hinge in place with some crazy glue or double sided tape while you drill the pilot hole. Even then however, sometimes your bit will become misaligned and then it becomes difficult to get the exact center again.
As well, a nice invention that helps enormously is the self centering vix bit. The self centering design of the vix bit ensures that the hole will be drilled absolutely in the center. They come in all manner of sizes and can be purchased at most woodworking retail stores.
The tapered vix casing fits into the hinge, perfectly aligning itself so that the drill bit inside the casing comes down exactly in the middle of the hinge hole.
The drill depth can be changed by means of loosening a set screw on the body, adjusting the drill bit to the desired depth and then locking the set screw again. Be sure to get a bit that is made from high speed steel which will stay sharp many times longer than similar bits made from high carbon steel. If you happen to need a new one, they do sell replacement bits that fit inside the casing so that you need not purchase an entirely new product.