tutorial for action constraints in fist making?

I tried use rigging to make fists using IK_solvers. but many people suggest using action constraints instead. can someone point me to a tutorial on how many bones to use for a finger in a hand? like do i need an ik bone or a null bone? and how to properly use action constraints to make this animation?

i wouldn’t use IK for the fingers (too much computation needed). actions constraints is much easier to animate, but tedious to set up (every bone that moves needs it#s own action constraint). it’s well documented at blender.org (documentation), though

I use to rig my hands using RVK´s. One slider/finger and one slider/fist.