There are lots of ways to hold a pick. My advice is (a) hold it however it works best for you, and (b) don't necessarily limit yourself to just one grip. The "side of the index finger" approach that you describe is quite common, but as a rule it doesn't work that well for me. I tend to hold the pick between the thumb and the tip of my index finger, rather than the side, sometimes adding my middle finger for extra support when I need to dig in. I find that this grip accomodates variations in how firmly I am holding the pick -- I can relax a little when I want the pick to have more "give" (like when I'm strumming a gentle rhythm) or hold it more firmly when I want to make a lead line stand out more prominently. Once you're accustomed to your grip on the pick, these variations happen on a semi-conscious level -- you think of the tone you're looking for in any given song/line/note, and your fingers pretty much know what they need to do without being told.

A lot of bluegrass guitar players do like the "side of the index finger" grip, because they can get a lot of power behind the notes that way. But there are advantages to other approaches as well, so I wouldn't be too quick to abandon what works for you for the sake of "doing it right".

As for Gorilla Snot, the stuff is out there, and evidently there's a market for it. But I think you're better off learning how to hold a pick without it; that way you can change your grip at will, and you aren't dependent on smearing sticky stuff on your fingers every time you want to play.