How To Finger Accurately And Play In Tune.
Section links: Intro Tuning Straight Wrist Hand Form Finger Placement Minimum Finger Movement Third Finger "Secret" Exercises
Keep your left wrist straight.
Most good fiddlers (and all classically trained violinists) keep the left wrist straight. That is, they don't allow the fiddle neck to come up against the palm of the hand.
This first photo shows the wrist bent and the palm up against the neck where it should not be. This isn't the form you want.
Without guidance, a bent wrist can seem more comfortable at first; but It's a trap. I think people fall into it because when they start out, there's no one there to say "Hey, look out! Don't go there."
This second photo shows the wrist straight and the palm well away from the neck.
This is pretty much what you want to see if you look in the mirror (with the image reversed, of course).
It might take a little effort to learn the straight wrist in the beginning, but the payoff is huge.
Why does it matter?
One reason is because of the physical structure of the forearm, wrist and hand. When you play, you're moving lots of tendons and muscles all the way from the elbow down to the ends of the fingers. If you keep your wrist straight, and gently arc your fingers over the strings, you'll be able to move these tendons and muscles more easily. If you bend your wrist, you put a kink in the pipe, so to speak. Things get bound up and don't move as freely.
Another reason the straight wrist matters is that it allows the fingers to "attack" the strings and fingerboard at the correct angle. More on that in the "Hand Form" part of this lesson.