I'd just be inclined to urge a note of caution regarding any assumption as to the glideslope indicated by the PAPIs.
As has been said, at commercial, etc., airports the PAPIs probably indicate around a 3 degree slope, whilst at other fields, if PAPI equipped, they may indicate a steeper slope, e.g. 4 degrees at Sherburn, I believe.
The moral, of course, as in all things aviation related, is not to make assumptions, but to look it up in the AIP.
As far as landings in general are concerned, I agree that there is no substitute for familiarity with the desired appearance of the runway when on final. Aiming for the numbers, 'flying the numbers' w.r.t. threshold speed, etc., and a flare leading to a hold off just above the runway, with idle power, until the aircraft settles gently onto the ground mainwheels first.
As I have seen elsewhere, the aim is to strike the planet a (gentle) glancing blow!