I'm a beginer and I have also struggled with holding the pick. I am heavy handed at times, and just put it down to that as struggled to hold the pick loose without dropping it. I started using a small piece of bluetac to stick the pick to my guitar when i wasn't playing as i kept losing them. I now use my pick with the small piece of bluetac and find that this helps me, and i no longer drop the pick while at the same time i can hold it loose and my strumming hand is more relaxed.