preparation on the firing point

[RobD]

For what its worth, I would recommend
(a) don't use a jacket and sling - use a rest. The sling etc will just make you hot and bothered.
(b) don't shoot when there is a competition going on
(c) don't bother with a spotting telescope, binoculars are fine
(d) shoot at 100 and 200 yds
(e) use your own gun
(f) if you have 50+ yr old eyes, an aperture rear sight gives invaluable pinhole-effect benefits. If its a No 4, you can make the hole a bit smaller to suit, for example with a bit of black card, or by painting the inside of the hole with matt black paint. When the sight picture just starts to dim, you have gone far enough.
(g) if you need to zero any sight (whether telescopic or iron sight) which you have not used on that rifle before, and if you can't use a zeroing range, then bore-sight it. By which I mean: prop the rifle up on cushions looking out of your lounge window, remove the bolt, and peer down the barrel until you can see a prominent distant object down the bore. Then, without moving the rifle, adjust the sight so that it fixes on the same thing. Then re-check and so on. Amazingly good at getting the sights adjusted to the correct setting for approx. 200 yds.
Hope that helps.
Rob