My personal prference is as follows.Arm action is usually better kept short and symmetric.
Many kids tend to straighten/extend the arms at the elbow after handbreak.In many cases this unnecessarily lengthens the action.Following handbreak,before the throwing arm begins to load by laying back/externally rotating the bend in the elbow needs to get back to about 90 degrees.So if you extend the arm,then flex back to 90,that's a lot more action to manage.(this is the way the "throwmax" brace works by preventing the flexing of the arm back to more than 90 degrees/giving the feel of the elbow staying at 90 degrees).
Shortening arm action can be accomplished by keeping the arm (both arms if you believe in symmetry)flexed at about 90 degrees(Clemens type handbreak) at the elbow and by pinching the shoulder blades together (so-called "scap loading" or more narrowly defined as "horizontal adduction" of the scapulae as described by nyma-n at se-tpro).
A full/pinch/scap load with the elbows elevated requires the arms to be well internally rotated first which is what showing the ball to center field and keeping the fingers on top at handbreak will do.
I use the following cues after Jeff Hodge(biomechanicbaseball/Centinella hospital/Dodgers) and Nyma-n.
Break the hands using symmetric arm action with the elbows up and the palms down (or palms out or thumbs pointing down,then lift (the elbows) and pinch (the scaps/shoulder blades.This position can be practiced and checked to see that arms are symmetric and internally rotated and elbows are up with scaps loaded creating what Nyma-n calls the "W" position,arms forming "W" shape as seen from bird's eye view.
A short arm action handbreak like this is done relatively later/quicker than the one followed by lots of arm extension.Better to flex the arms and sight with the elbow.
