Pinch gripping involves squeezing the extended fingers towards the thumb without flexing individual digits, such as you'd experience holding a textbook.
Most strength athletes use plate pinches (holding two 25 or 45 pound plates together), but there are alternatives. For example, using two dumbbells allows you to have access to a greater range of weights. That makes it much easier to progress in smaller increments.
Mike used to like Functional Training. He used to think Mike Mentzer was kind of a bonehead. Now he's not so sure about the former or the latter, along with a whole lot of other things. If his current rate of "unlearning" continues, he soon won't know anything!