The method I was taught many years ago to has never failed me.

EO/IC rule (Exhaust Opening and Intake Closing). using a remote starter button/ switch to bump the motor around

Set the intake valve when the exhaust valve is beginning to open. This will put the intake lifter at the base circle which is where you want it to be.

Then set the exhaust valve when the intake valve is almost closed.

If adjusting hydraulics, loosen the adjuster until there is noticeable play between the rocker and pushrod / valve

While rolling the pushrod between two finger tips, begin slowly tightening the adjuster.

Just as you hit Zero lash you will feel a slight but distinct resistance. You can loosen a 1/4 turn or so and retighten to confirm several times until yo get the "hang" of it.
the above resistance will be felt even with empty lifters. You will also note the " free play" is gone.

From that point, depending on adjusters threads per inch determines how far to tighten. Most are 3/8 x 24. So if one divides 1inch by 24 =.0416" per turn. All camshaft Manufacturers' I am aware of recommend. 0.020" to .040" preload.

So I use 1/2 turn beyond zero lash.

And in closing years ago I soaked and pumped up a set of hydraulics before installing them. After 3 days several were still holding the valves open and would not bleed down. Haven't done that since

The same "EO/IC rule (Exhaust Opening and Intake Closing) method can be used with solids using feeler gauges to set the lash.
I prefer to start at the front valve, and work my way back 1 at a time. Then repeat on the other side