The platform should be a typical benchrest rig, on a solid concrete foundation, with sand-padded adjustable front stand, and a coarse sand bag and 'owl ears' bag for the butt. Your own shoulder should be the only thing absorbing recoil. That's for consistency and because most commercial rifles aren't made to be clamped down to some solid device. The support rests should be sort of like what this cat's using:
http://video.google.com/videoplay?do...6798795391569#
With a bolt-action rifle, square a picatinny rail on the action, mount the scope on that with turret adjustments to zero. Put up a target at 50 yards, pull out the bolt and look through the bore. Center the bore on the bullseye. Without disturbing the rifle, adjust the scope to also center on the bullseye.
On a calm, cool day, take a clean/cold-bore shot just to confirm that you hit the paper near the bullseye, then ignore it. (The impact of most rifles I've used settle somewhere away from that first shot for whatever reason).
At a 100 meter target, take a second shot carefully aiming at the bullseye. After that shot, again aim exactly on the bullseye's center. Then without disturbing the rifle at all, adjust the range and windage knobs so that the crosshair is on where that second shot hit.
With one warm shot, you will have zero'd your rifle. No need to chase the point of impact all over the place with a whole box of ammo.
Record the turret settings, and if the scope model allows, set the caps to zero at that setting. If you're using the same scope for multiple rifles, keep your 'go-to' rifle as the main reference (either with those turret settings or the zero-set caps). Then mount the scope on each of the other rifles, zero'ing each in succession the same way, except just write down the turret adjustments for each. The turret adjustment for each will be the zero that you set the scope at, for that particular rifle.
With a good scope base, you'll be able to swap the scope back onto any rifle and have it zero'd to a fraction of a mil with the numbers you wrote down. Fine-tuning the zero after swapping the scope back usually will only take one or two clicks.
It's best to zero to 100 yards if you're using the turrets to set clicks for range and windage adjustments, from a reference or 'dope' card. If you think you will be 'snap-shooting' then you will want zero at close range anyway. If you will be shooting at 300 or 500 yards or more, then you will probably be setting up for a careful long shot. Then you should have enough time to glance at the dope card, and crank the turrets the right number of clicks.