Again this is a matter for the individual to discover : there is no "one way to hold it for all" option. I for example, use tiny tear drop picks (mostly) and I have about 1/8 of an inch of the tip exposed.By playing like this I have my thumb muting the string above if I have just played it and I'm moving to the next string below it to pick - think quick triplet type sound, my thumb mutes or kills the the string from ringing out.When holding a pick how much of the pick should be protruding from the finger and thumb .I try to get at least half so my finger and thumb don't hit the strings, is this a good technique for a learner ?