Summarize the following:
Wear it just long enough for your odor to rub off. Put the sock over your hand, with your fingers holding the catnip dangling down inside the bottom of the sock. Then twist the end of the sock. It doesn't have to be perfectly secure, just enough to allow you to re-wrap the sock with multiple layers. You should now have a new "layer" to add to the toy. You won't need too much. Not all cats like catnip, but cats that do like catnip tend to be quite sensitive to it. One theory on why catnip excites cats is that it acts on the hypothalamus, triggering a predatory reaction. Some research suggests certain molecules in catnip act as an opioid on cats, triggering the pleasure center in cats' brains. Not all cats are affected by catnip. Only about 30-70% of all cats will react to catnip. You may want to make this knot somewhat loose, so that your cat will be able to access the catnip. "Working" for food allows cats to indulge in the natural predatory instincts that all cats are born with. Some cats are immune to catnip, but those that aren't immune will find the toy irresistible. Even if your cat does not like catnip, it will certainly enjoy playing with the toy. Your cat will be able to smell you on the sock, and it may come to associate your smell with the excitement and joy of playing with catnip, making this a great toy for newly adopted cats.
Wear an old sock for a few hours. Take a large pinch of catnip in your hand. Drop the catnip in the toe. Grip the toe of the sock with the catnip inside and pull the sock off. Repeat this, adding a bit more catnip for every layer. Tie a knot in the end of the sock. Give the toy to your cat.