I am currently in the Milwaukee Irishfest Summer School taking the banjo class with Enda Scahill of WeBanjo3. If you are not familiar with him, he is the author of two terrific tutorials and co-author of a third tune book with Martin Howley that I think serves as a third upper level tutorial.
Enda has very specific ideas about how you hold the pick and gives what I think are logical reasons for using the "natural" hold which uses the least amount of tension of all the styles of hold. For beginners, this is the best way to start because it promotes efficiency and accuracy, two qualities you will treasure later on. While there are other ways to hold the pick (and you may eventually migrate to one of them), this is the one that is promoted by more teachers in my experience.
Here is a video of Enda showing the how and whys of this pick hold:
Here is a video I took several years ago showing Enda playing an incredible passage with this grip:
Here is Enda talking about posture and relaxation from The O'Flaherty Retreat in 2009:
Next Lesson: Another Tune, (this time easier.)