It's not all about the Pitcher...
Most discussion on holding runners centers on the pitcher's move to first. In fact WebBall has an entire pitcher's pick-off playbook.
But it's the 1st baseman who is the first line of defense in keeping runners from advancing.
If you're not set up at first correctly, and you don't know how to make the tag, it doesn't matter how good the pitcher's jump turn - you won't be picking off anyone.
...or about pick-offs
Of course, the truth is that few pick-off throws succeed in getting an out. That doesn't matter. If you can execute the move effectively, then you keep the runner one step closer, or delay his jump, or discourage their coaches from even thinking about a steal.
Ready for the throw

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Your first priority is proper positioning so that you can take the throw from the pitcher (ideally belt high) and get the glove down to the bag (and runner's leg) quickly. For lefties (preferred at first) start with the heel of your right foot up against - or close to the inside corner of - the bag. And make sure you track the ball into your trapper and squeeze it there, before you bring the glove into the tag zone.
Handling high throws

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Pitchers aren't perfect. The pick-off throw could sail high, and you must be ready to react. First priority is to reach up, or out, and snag the ball. If you're still positioned at your starting corner, it could be worth the effort to bring the ball down into the tag zone.
But if the throw requires you to step away from the bag, then just make certain of the catch, don't try to do too much. In fact, because the runner is busy diving, and the first-base coach may also be focused on the anticipated tag at the bag, when you step away without attempting a late, out-of-position sweep tag, you give less away - they remain uncertain as to what happened, or if the throw would have been in time. Uncertainty keeps runners closer.
Blocking low throws

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If the pitcher's throw is low and to the runner's side - all you can hope for is that the runner's sliding/diving body keeps the ball right there.
If the low throw (or bounce) is to your side of the bag (as shown), then it's no longer about a catch and sweep tag, first priority is to block the ball from scooting past you or through your legs. In practice ask for some of those to see which technique you prefer - the catcher's drop to the knees, or the side turn with one knee down like an outfielder's safety catch (shown).
Watch for additional techniques coming soon to this page for throws coming from the catcher, for when you are playing behind the runner, and for right-handers playing first.