Holding on to a slick guitar pick is a challenge for experienced guitar players. Imagine what it's like for beginners.
When I started playing, the slick picks I owned slid between my fingers, which made it very difficult to strum guitar strings with any accuracy. The real danger, however, is that constantly adjusting your thumb, fingers and hands to accomodate the shifting pick will lead you to develop bad form, which will impede your progress as a player.
During my search for a superb easy-grip pick, I settled for playing with the side of my thumb. I tried all kinds of picks, including a slightly rough pick that didn't quite do it, before I purchased Snarling Dogs Brain Picks in two different thicknesses. The pick area that you press between your thumb and index finger is as rough as sandpaper, which makes holding and controlling the pick a lot easier.
I initially bought two thicknesses (they're very inexpensive) of Snarling Dogs Brain Picks to test. I found the .73 MM picks to be too flexible. When they strike the strings, they make a card-flipping-on-bike-spokes sound. The 1.00 MM thickness was just right.
Snarling Dogs Brain Picks are sold by the dozen in a rad metal dispenser. I recommend them to any player who is having trouble holding a pick.
Snarling Dogs Brain Picks are much easier to hold than slick picks. The photo below shows a close-up of a 1.00MM thickness pick. Both sides are as rough as sandpaper, which makes them much easier to hold. This is critical for players who are tired of adjusting their thumb and index finger to keep a pick properly aligned for striking guitar strings.