If you have a correct grip, you can grip the club as firm as you want. Most players with a faulty grip feel they have to strangle the club because they know they're going to lose it. But I believe everything comes from the center. Most sports are done with balance, like gymnastics or karate, and done from the center. Even linebackers in football move from the center.
Balance is the most important thing in the swing.
To have a solid center, you must bent slightly forward at the waist and your knees must be flexed so you can really feel almost like you are in a linebacker position. You don't feel like you are going to fall over. Your weight is equally distributed. A problem with many amateurs, and you mentioned this as well, is they think about too many mechanics while competing. Mechanics is an important part of the game, but scoring is the most important part.