A picture is worth a thousand words. Cornell Feline Health Center has been kind enough to develop and post a cat-pilling video.
I don't like to wrap my patients in a towel to pill them - most are fine without it. I will either scruff the back of the cat's head or grasp the whole head from above, depending on the cat's temperament. You just need to experiment with a few variables to see what works best in your individual case.
If you have to give several different pills, we carry gelatin capsules that you can often stuff everything into so you only have to pill the cat once.
Cornell also has a video on how to give a cat liquid medication:
I just have ONE question: How did we ever survive without the wonders of the internet??