Bow hand done right: web of the hand in the lowest point of the grip, fingers loose, pressure through the thumb pad. Stop clenching and tighten your groups.
The honest answer up front: your bow hand should not hold the bow, it should only support it. The pressure comes from the pull of the string, not from your fist [1]. It sounds minor, but this is where many beginners build their own scatter: if you hold on, you push the bow sideways at the moment of release.
There is measured data for this. In an EMG study (muscle measurement with skin electrodes) of 10 elite and 10 beginner archers, the main difference at the bow arm was this: the elite archers not only relax the finger flexors, they also activate the finger extensor (M. extensor digitorum) more strongly [1]. In plain words: the hand opens up rather than forming a fist. The authors explain that this keeps the forward movement of the bow after release undisturbed [1].
How hard is it? You understand the principle in one session. From experience, though, it takes weeks of regular repetition before your body stops gripping on its own. The evidence comes from recurve; for compound and barebow the principle is a TRANSFER, only the grip shape differs.
The web of the hand, the skin between thumb and index finger, sits in the lowest point of the grip. According to the DSB position model, the pressure point for right-handed archers lies to the right of the life line [2], the big line curving around your thumb pad. Left-handers mirror this. Milestone: you find this position three times in a row with your eyes closed.
The model gives an angle of about 45° for the bow hand [2]. Anchor: the hand is neither flat nor vertical but tilted, roughly halfway between the two. That sends the pressure through the thumb pad rather than the middle of the palm.
The fingers rest at the front of the grip without wrapping around it. The index finger hangs, it does not clamp. The pressure arises because the string pushes the bow into your hand [1]. Test it: if you could drop the bow briefly after the draw and only the sling would hold it, your hand is right.
The bow arm is extended; the DSB model gives about 30° for the rotation and set angle of the extended arm (the "support line") [2]. Your coach is best placed to show you how that feels on your body. Important: the wrist stays mobile.
At release the hand should hold nothing. According to the model, the bow hand keeps moving toward the target and the wrist folds downward [2]. Your bow tips forward into the sling. Milestone: 10 shots in a row where the bow tips forward cleanly and you do not catch it.
Shoot a few arrows deliberately with a sling and a completely open hand, fingers lying loose. If the bow falls cleanly forward after release, you have the feeling of "supporting instead of gripping". If it tips sideways or your hand snaps shut, you are still clenching.
The web of the hand sits in the lowest point of the grip, the hand is angled at about 45° [2], and the fingers rest loosely at the front. The pressure comes from the pull of the string, not from your fist [1].
According to coaching doctrine, gripping creates a sideways torque on bow and arrow at release [1]. Elite archers therefore relax the finger flexors and activate the extensors [1].
You don't have to, but it helps: it catches the bow and shows you whether you are still holding on. This is a widespread practice recommendation, not a study finding.
The measurements I read come from recurve [1]. The principle "support instead of grip" is carried over to compound and barebow (TRANSFER), but the grip shape is different there.
The Draw: Pull From Your Back, Not Your Arm