Bubbie has you covered here. And I agree that the biggest mistake folks make is at the beginning.
You have to have the piston at TDC of the compression stroke to do both PRs. So if you watch your exhaust open then close, and the intake open and then close, when the piston gets to the top is the compression stroke TDC.
Then collapse your PRs all the way and go have dinner. Better yet, take the PRs out and clean them making sure you know which is which (exhaust and intake). It is a good idea to make sure the oil path through the center of the PRs is completely cleaned out of any crud.
When 15-20 min have passed since collapsing the PRs and the lifters have had time to completely extend, then reinstall the PR you are gonna do first. Slowly extend the end down onto the lifter until it has just made contact and will not wiggle side to side, but still turns easily. This is zero lash.
Then adjust your PR the correct number of turns to accomplish about .120-.140" down (assuming standard lifter plunger travel of about .200" total).
This seems to be the setting most folks have the least problems with.
Repeat for the other PR, and then let it sit for 15-20 min until you can twirl the PRs with your thumb and index finger. At that point, button up the PR covers and rotate the engine to the TDC of the compression stroke of the other cylinder and repeat the process for that one.
Cheers,
TQ